<PAGE>   1
                                                                    EXHIBIT 4.03

            Amendment to the Revolving Credit and Term Loan Agreement
                               (Fleet Letterhead)

February 28, 2001


Nashua Corporation
11 Trafalgar Square
2nd Floor
Nashua, NH  03063

Rittenhouse Paper Company
250 South Northwest Highway
Parkridge, IL 60068

Rittenhouse, L.L.C.
250 South Northwest Highway
Parkridge, IL  60068

RE:  FINANCIAL COVENANTS VIOLATION WAIVER

Ladies and Gentlemen:

     Reference is hereby made to that certain Revolving Credit and Term Loan
Agreement dated April 14, 2000 as amended by letter agreement dated October 23,
2000 (the "Credit Agreement") by and among Nashua Corporation ("Nashua"),
Rittenhouse, L.L.C. ("Rittenhouse"), Rittenhouse Paper Company ("RPC") (Nashua,
Rittenhouse and RPC are referred to individually as a "Borrower" and
collectively as the "Borrowers") and Fleet National Bank (successor by merger to
Fleet Bank-NH) ("Fleet"), as a Lender and as an Agent for itself and the other
Lender, LaSalle Bank National Association ("LaSalle") and other lenders from
time to time as a party thereto (collectively, the "Lenders"). Capitalized terms
used herein which are not otherwise defined, shall have the meaning given to
such terms in the Credit Agreement.

     The purpose of this correspondence is to set forth the terms and conditions
of the Lenders' agreement to waive the Borrowers' violations of the Total Funded
Debt to EBITDA Ratio and the Fixed Charge Coverage Ratio as set forth in
Sections 8(b) and 8(c) in the Credit Agreement for the fourth quarter ending
December 31, 2000. In consideration of the Lenders agreeing to waive the
foregoing Total Funded Debt to EBITDA Ratio and the Fixed Charge Coverage Ratio
violations for said fourth quarter, the Borrowers agree to pay a waiver fee in
the amount of $169,500 upon execution of this Letter Agreement. Also, in
consideration of said waivers, the Borrowers and the Lenders agree to amend the
Credit Agreement and other Loan Documents as follows:

1.   Section 2.1(a) of the Credit Agreement is hereby amended by deleting the
     phrase "Thirty Five Million Dollars ($35,000,000)" appearing three times in
     the first paragraph thereof and replacing said phrase with "Thirty Million
     Dollars ($30,000,000)".

2.   Section 2.1(a) of the Credit Agreement is hereby further amended by
     deleting the amounts appearing in a portion of the grid under Revolving
     Loan Commitment for Fleet, LaSalle and Total and replacing them as follows:

          LENDER                    REVOLVING LOAN COMMITMENT

          Fleet                            $16,363,635
          LaSalle                          $13,636,365
                                           -----------
          TOTAL                            $30,000,000
                                           ===========

<PAGE>   2

February 28, 2001
Page 2

     The balance of the grid appearing in said Section 2.1(a) of the Credit
Agreement shall remain unchanged.

3.   Section 2.2(d) of the Credit Agreement is hereby amended by deleting the
     phrase "1.25%" and replacing said phrase with "2.25%".

4.   Section 2.6 of the Credit Agreement is hereby generally amended to reflect
     that the applicable margins shall no longer be based upon Nashua's net
     income and that the pricing grid set forth in said Section is hereby
     deleted in its entirety and replaced with the following which shall be
     effective commencing January 1, 2001:

<TABLE>
<CAPTION>
         REVOLVER BASE        TERM BASE        REVOLVER LIBOR      TERM LIBOR
          RATE MARGIN        RATE MARGIN           MARGIN            MARGIN
<S>                          <C>               <C>                 <C>
               1%                1-1/2%               3%              3-1/2%
</TABLE>

5.   Section 2.6(e) of the Credit Agreement is hereby amended by (a) deleting
     the phrase "$1,176,471 (being one seventeenth of the initial face amount of
     the Term Loan)" and replacing said phrase with: "$765,000"; and (b) adding
     the following at the end of said section: "In addition to the above
     mentioned quarterly principal payments, the Borrowers shall pay to the
     Agent for the pro rata benefit of the Lenders principal reduction payments
     in the amount of $2,900,000 on or before the earlier of June 30, 2001 or
     that date five days after the Borrowers receive their federal tax refund,
     and $4,100,000 on or before the earlier of September 30, 2001 or that date
     five days after the Borrowers receive their federal tax refund."

6.   Pursuant to Section 6.10 of the Credit Agreement, the Lenders hereby
     consent to Andrew Albert serving as Chairman and Chief Executive Officer of
     Nashua.

7.   Section 7.7 of the Credit Agreement is hereby amended by deleting the
     phrase "commencing January 1, 2001, in excess of $5,500,000 in the
     aggregate in any one fiscal year thereafter" appearing in the first
     sentence thereof and replacing said phrase with "commencing January 1,
     2001, in excess of $3,500,000 in the aggregate in any one fiscal year
     thereafter".

8.   Section 8 of the Credit Agreement is hereby amended by deleting it in its
     entirety and replacing it with the following:

          "ss.8. FINANCIAL COVENANTS. Each Borrower covenants and agrees that,
          so long as any Loan or Note is outstanding or the Lenders have any
          Available Revolving Commitment, the Borrowers shall maintain or
          achieve the following financial covenants subject to paragraph (a)
          hereof:

          (a)  COVENANT CALCULATIONS. The covenants calculations in ss. 8(b) and
               ss. 8(c) below shall be based upon the Borrowers' consolidated
               financial statements. Such covenant compliance shall be tested
               quarterly as of the end of each fiscal quarter. For purposes of
               determining covenant compliance for ss. 8(b), EBITDA will be
               annualized and the covenant shall be calculated quarterly as of
               the end of each fiscal quarter on a going forward basis ramping
               to a trailing four quarter basis. For purposes of determining
               covenant compliance for ss. 8(c), said covenant shall be
               calculated quarterly as of the end of each fiscal quarter on a
               cumulative going forward basis ramping to a trailing four quarter
               basis.

          (b)  TOTAL FUNDED DEBT/EBITDA. Tested as set forth in ss. 8(a), the
               ratio of the Borrowers' Total Funded Debt to EBITDA shall not
               exceed the following maximum levels for the period indicated:

<PAGE>   3

February 28, 2001
Page 3

<TABLE>
<CAPTION>
                  PERIOD                                           MAXIMUM
            (EBITDA ANNUALIZED)                                     LEVEL

<S>                                                              <C>
            First Quarter 2001                                   5.0 to 1.0
            First and Second Quarter 2001                        4.5 to 1.0
            First through Third Quarter 2001                     3.5 to 1.0
            Trailing Four Quarters at all times thereafter       3.0 to 1.0
</TABLE>

          "Total Funded Debt" means the aggregate amount of all interest bearing
          obligations of the Borrowers. "EBITDA" is the sum of the Borrowers'
          GAAP net income (minus extraordinary income) plus Interest Expense,
          taxes, depreciation and amortization. During the first quarter of 2001
          only, unusual and restructuring charges up to $300,000 will be
          excluded from the calculation of this covenant.

          (c)  FIXED CHARGE COVERAGE RATIO. Tested as set forth in ss. 8(a), the
               Borrowers shall maintain a Fixed Charge Coverage Ratio of at
               least 1.1 to 1.0. The Fixed Charge Coverage Ratio means the ratio
               of (I) the sum of the Borrowers' EBITDA minus the sum of
               unfinanced Capital Expenditures, dividends and cash taxes to (ii)
               the sum of Interest Expense and current maturities of long term
               debt paid during the measured period excluding payment from tax
               refunds enumerated in revised Section 2.6(e)."

9.   On or before that date three (3) months from the date hereof, the Borrowers
     shall provide and grant the Lenders a first priority security interest in
     additional Collateral in the form of additional machinery and equipment of
     Nashua or Rittenhouse with an orderly liquidation value of at least Five
     Million Dollars ($5,000,000). The Borrowers agree to execute and deliver
     any and all documents that the Agent requests to carry out the foregoing,
     including, without limitation, an amendment to the Loan Documents,
     additional financing statements, an opinion of counsel (including Delaware
     counsel) and a detailed listing of said machinery and equipment, all of
     which must be in form and substance acceptable to the Lenders.

10.  The Borrowers hereby grant to and confirm unto the Agent, as collateral
     agent for the Lenders, a security interest in or mortgage upon the
     Collateral described in the Security Documents to secure the Obligations,
     as they may be amended, modified, extended, restated or renewed from time
     to time, and the terms and conditions of said Security Documents are hereby
     ratified and confirmed.

11.  The Notes shall be amended pursuant to Amendments to Revolving Credit Note
     and Amendments to Term Note in the forms attached hereto as Exhibit A.

     This Letter Agreement shall constitute an amendment to the terms and
conditions of the Loan Documents as well as the Credit Agreement. All references
to the Loan Documents, shall hereinafter refer to such documents as amended. The
provisions of the Loan Documents, as modified herein, shall remain in full force
and effect in accordance with their terms and are hereby ratified and confirmed.

     The Borrowers shall execute and deliver such additional documents and do
such other acts as the Lenders may reasonably require to implement the intent of
this Letter Agreement fully. The Borrowers shall pay all costs and expenses,
including but not limited to, attorneys' fees, incurred by the Lenders in
connection with this Letter Agreement. To the extent not otherwise paid from the
Revolving Credit Loan, the Agent, at its option, but without any obligation to
do so, may advance funds to pay any such costs and expenses that are the
obligations of the Borrowers, and all such funds advanced shall bear interest at
the highest rate provided in any Notes. This Letter Agreement may be executed in
several counterparts by the Borrowers and the Lenders, each of which shall be
deemed an original but all of which together shall constitute one and the same
Agreement.

<PAGE>   4

February 28, 2001
Page 4

     If the foregoing is acceptable, please sign below to indicate your consent
and agreement to the above.

                                   Very truly yours,

                                   FLEET NATIONAL BANK (successor by merger
                                   To FLEET BANK-NH), As Agent


<TABLE>
<S>                                <C>
/s/ Diane A. Anderson              By: /s/ John A. Hopper
--------------------------------      --------------------------------
Witness                                    John A. Hopper, Its Duly
                                           Authorized Senior Vice President

     Agreed and consented to:

                                   NASHUA CORPORATION

/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    /s/ John L. Patenaude           , Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------

                                   RITTENHOUSE PAPER COMPANY


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    /s/ John L. Patenaude           , Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------


                                   RITTENHOUSE, L.L.C.


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    /s/John L. Patenaude            , Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------
</TABLE>

STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 15 day of March,
2001, by John A. Hopper, the duly authorized Senior Vice President, of FLEET
NATIONAL BANK (successor by merger to Fleet Bank-NH), a national bank organized
under the laws of the United States, on behalf of the same.

                                   /s/ Diane A. Brodeur
                                   -------------------------------------
                                   Notary Public
                                   My Commission Expires:  May 12, 2004
                                   Notary Seal

<PAGE>   5

February 28, 2001
Page 5


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28TH day of
February 2001, by John Patenaude, the duly authorized VP Finance & CFO of NASHUA
CORPORATION, a Delaware corporation, on behalf of the same.

                                   /s/ Linda J. Madden
                                   -------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal



STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28TH day of
February 2001, by John Patenaude, the duly authorized VP Finance & CFO of
RITTENHOUSE PAPER COMPANY, an Illinois corporation, on behalf of the same.

                                   /s/ Linda J. Madden
                                   -------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal



STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28TH day of
February 2001, by John Patenaude, the duly authorized VP Finance & CFO of
RITTENHOUSE, L.L.C., a Illinois limited liability company, on behalf of the
same.

                                   /s/ Linda J. Madden
                                   -------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal

<PAGE>   6

February 28, 2001
Page 6


           LENDER COUNTERPART SIGNATURE PAGE TO LETTER AGREEMENT AMONG
     NASHUA CORPORATION, RITTENHOUSE PAPER COMPANY AND RITTENHOUSE, L.L.C.,
                 AS BORROWERS AND FLEET NATIONAL BANK, AS AGENT


     Agreed and Consented to:

                                   LASALLE BANK NATIONAL ASSOCIATION,
                                   As Lender


                                   By: /s/ Brian Sullivan
--------------------------------      ------------------------------------------
Witness                               Brian Sullivan                  , Its Duly
                                      --------------------------------
                                      Authorized  Assistant Vice President
                                                --------------------------------

STATE OF ILLINOIS
COUNTY OF COOK

     The foregoing instrument was acknowledged before me this 14 day of March,
2001, by Brian L. Sullivan, the duly authorized Asst. Vice President, of LaSalle
Bank National Association, a national banking association, on behalf of the
same.


                                   /s/ Effie Dale Scott
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  March 24, 2003
                                   Notary Seal

<PAGE>   7

February 28, 2001
Page 7


           LENDER COUNTERPART SIGNATURE PAGE TO LETTER AGREEMENT AMONG
     NASHUA CORPORATION, RITTENHOUSE PAPER COMPANY AND RITTENHOUSE, L.L.C.,
                 AS BORROWERS AND FLEET NATIONAL BANK, AS AGENT


     Agreed and Consented to:

                                   FLEET NATIONAL BANK (successor by merger
                                   To FLEET BANK-NH), as Lender


/s/ Diane A. Brodeur               By: /s/ John A. Hopper
--------------------------------   ----------------------------------------
Witness                                    John A. Hopper, Its Duly
                                           Authorized Senior Vice President


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 15 day of March,
2001, by John A. Hopper, the duly authorized Senior Vice President, of FLEET
NATIONAL BANK (successor by merger to Fleet Bank-NH), a national bank organized
under the laws of the United States, on behalf of the same.


                                   /s/ Diane A. Brodeur
                                   ----------------------------------------
                                   Notary Public
                                   My Commission Expires:  May 12, 2004
                                   Notary Seal

<PAGE>   8

                                                        EXHIBIT 4.03 (continued)

                             AMENDMENT TO TERM NOTE


     THIS AMENDMENT (the "Amendment"), is made as of the 28th day of February,
2001, by and among LASALLE BANK, NATIONAL ASSOCIATION, a national banking
association with a principal place of business at 135 LaSalle Street, Chicago,
IL 60603 (the "Lender") and NASHUA CORPORATION, a Delaware corporation with its
principal place of business at 11 Trafalgar Square, Nashua, New Hampshire 03063,
RITTENHOUSE PAPER COMPANY, an Illinois corporation with a principal place of
business at 250 South Northwest Highway, Parkridge, Illinois 60068 and
RITTENHOUSE, L.L.C., an Illinois limited liability company with a principal
place of business at 250 South Northwest Highway, Parkridge, Illinois 60068
(collectively, the "Borrower").


                              W I T N E S S E T H:


     WHEREAS, the Borrower, the Lender, Fleet National Bank, as agent, and
certain other Lenders entered into a Revolving Credit and Term Loan Agreement
dated April 14, 2000, as amended (the "Credit Agreement"), providing for loans
from the Lender to the Borrower and have executed certain documentation in
connection therewith (the "Loan Documents");

     WHEREAS, the Lender and the Borrower have agreed to amend certain
provisions of the Term Note dated April 14, 2000 made payable by the Borrower to
the Lender (the "Term Note"), issued pursuant to the Credit Agreement as more
fully set forth below.

     In consideration of One Dollar ($1.00) and other valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, the Lender and the
Borrower hereby agree as follows:

     1.   AMENDMENT TO TERM NOTE. The terms of the Term Note are hereby amended
by adding the following sentence to the first paragraph thereof immediately
after the phrase "in seventeen (17) equal consecutive quarterly payments as
provided in the Credit Agreement": "In addition to the foregoing quarterly
principal payments, the Borrower promises to make two principal reduction
payments as more fully set forth in Section 2.6(c) of the Credit Agreement".

     2.   COLLATERAL, ETC. The Loan Documents and the Collateral, as such term
is defined in the Credit Agreement, shall continue to secure the payment of the
Term Note, as hereby modified.

     3.   CONTINUING EFFECT. Except as modified herein, the provisions of the
Term Note remain in full force and effect in accordance with their terms, which
are hereby ratified and confirmed. All references to the Term Note in the Loan
Documents shall be deemed to refer to the Term Note, as amended.

     4.   COUNTERPARTS. This Amendment may be executed in several counterparts
by the Borrower and the Lender, each of which shall be deemed an original but
all of which together shall constitute one and the same Agreement.

<PAGE>   9

Page 2


Executed as of the date first above written.

                                   NASHUA CORPORATION


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------       ------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                      ---------------------


                                   RITTENHOUSE PAPER COMPANY


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                      ---------------------


                                   RITTENHOUSE, L.L.C.


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------

<PAGE>   10

Page 3

     Agreed and consented to:

                                   LASALLE BANK, NATIONAL
                                   ASSOCIATION


                                   By: /s/ Brian Sullivan
--------------------------------      ------------------------------------------
     Witness                               Brian Sullivan, Its Duly
                                           --------------
                                           Authorized  Assistant Vice President
                                                     ---------------------------

STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of NASHUA CORPORATION, a Delaware corporation, on behalf of the same.


                                   /s/ Linda J. Madden
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of RITTENHOUSE PAPER COMPANY, an Illinois corporation, on behalf of the
same.


                                   /s/ Linda J. Madden
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal

<PAGE>   11

Page 4


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

    The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President
Finance and CFO of RITTENHOUSE, L.L.C., an Illinois limited liability
company, on behalf of the same.


                                   /s/ Linda J. Madden
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal


STATE OF ILLINOIS
COUNTY OF COOK

     The foregoing instrument was acknowledged before me this 14 day of March,
2001, by Brian L. Sullivan, the duly authorized Asst. Vice President, of LaSalle
Bank National Association, a national banking association, on behalf of the
same.


                                   /s/ Effie Dale Scott
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  March 24, 2003
                                   Notary Seal

<PAGE>   12

                                                        EXHIBIT 4.03 (continued)

                             AMENDMENT TO TERM NOTE


     THIS AMENDMENT (the "Amendment"), is made as of the 28th day of February,
2001, by and among FLEET NATIONAL BANK (successor by merger to Fleet Bank-NH), a
national bank organized under the laws of the United States with a principal
place of business at 1155 Elm Street, Manchester, New Hampshire 03101 (the
"Lender") and NASHUA CORPORATION, a Delaware corporation with its principal
place of business at 11 Trafalgar Square, Nashua, New Hampshire 03063,
RITTENHOUSE PAPER COMPANY, an Illinois corporation with a principal place of
business at 250 South Northwest Highway, Parkridge, Illinois 60068 and
RITTENHOUSE, L.L.C., an Illinois limited liability company with a principal
place of business at 250 South Northwest Highway, Parkridge, Illinois 60068
(collectively, the "Borrower").


                              W I T N E S S E T H:


     WHEREAS, the Borrower, the Lender, Fleet National Bank, as agent, and
certain other Lenders entered into a Revolving Credit and Term Loan Agreement
dated April 14, 2000, as amended (the "Credit Agreement"), providing for loans
from the Lender to the Borrower and have executed certain documentation in
connection therewith (the "Loan Documents");

     WHEREAS, the Lender and the Borrower have agreed to amend certain
provisions of the Term Note dated April 14, 2000 made payable by the Borrower to
the Lender (the "Term Note"), issued pursuant to the Credit Agreement as more
fully set forth below.

     In consideration of One Dollar ($1.00) and other valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, the Lender and the
Borrower hereby agree as follows:

     1.   AMENDMENT TO TERM NOTE. The terms of the Term Note are hereby amended
by adding the following sentence to the first paragraph thereof immediately
after the phrase "in seventeen (17) equal consecutive quarterly payments as
provided in the Credit Agreement": "In addition to the foregoing quarterly
principal payments, the Borrower promises to make two principal reduction
payments as more fully set forth in Section 2.6(c) of the Credit Agreement".

     2.   COLLATERAL, ETC. The Loan Documents and the Collateral, as such term
is defined in the Credit Agreement, shall continue to secure the payment of the
Term Note, as hereby modified.

     3.   CONTINUING EFFECT. Except as modified herein, the provisions of the
Term Note remain in full force and effect in accordance with their terms, which
are hereby ratified and confirmed. All references to the Term Note in the Loan
Documents shall be deemed to refer to the Term Note, as amended.

     4.   COUNTERPARTS. This Amendment may be executed in several counterparts
by the Borrower and the Lender, each of which shall be deemed an original but
all of which together shall constitute one and the same Agreement.

<PAGE>   13

Page 2


     Executed as of the date first above written.

                                           NASHUA CORPORATION


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------



                                   RITTENHOUSE PAPER COMPANY


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------



                                   RITTENHOUSE, L.L.C.


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------

<PAGE>   14

Page 3

     Agreed and consented to:

                                           FLEET NATIONAL BANK

/s/ Diane A. Brodeur               By: /s/ John A. Hopper
-------------------------------       -------------------------------------
Witness                                    John A. Hopper, Its Duly
                                           Authorized Senior Vice President

STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of NASHUA CORPORATION, a Delaware corporation, on behalf of the same.


                                   /s/ Linda J. Madden
                                   ----------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of RITTENHOUSE PAPER COMPANY, an Illinois corporation, on behalf of the
same.


                                   /s/ Linda J. Madden
                                   ----------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal

<PAGE>   15

Page 4


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of RITTENHOUSE, L.L.C., an Illinois limited liability company, on behalf
of the same.


                                   /s/ Linda J. Madden
                                   ----------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 15 day of March,
2001, by John A. Hopper, the duly authorized Senior Vice President, of FLEET
NATIONAL BANK (successor by merger to Fleet Bank-NH), a national bank organized
under the laws of the United States, on behalf of the same.


                                   /s/ Diane A. Brodeur
                                   ----------------------------------------
                                   Notary Public
                                   My Commission Expires:  May 12, 2004
                                   Notary Seal

<PAGE>   16

                                                        EXHIBIT 4.03 (continued)

                       AMENDMENT TO REVOLVING CREDIT NOTE


     THIS AMENDMENT (the "Amendment"), is made as of the 28th day of February,
2001, by and among LASALLE BANK, NATIONAL ASSOCIATION, a national banking
association with a principal place of business at 135 LaSalle Street, Chicago,
IL 60603 (the "Lender") and NASHUA CORPORATION, a Delaware corporation with its
principal place of business at 11 Trafalgar Square, Nashua, New Hampshire 03063,
RITTENHOUSE PAPER COMPANY, an Illinois corporation with a principal place of
business at 250 South Northwest Highway, Parkridge, Illinois 60068 and
RITTENHOUSE, L.L.C., an Illinois limited liability company with a principal
place of business at 250 South Northwest Highway, Parkridge, Illinois 60068
(collectively, the "Borrower").


                              W I T N E S S E T H:


     WHEREAS, the Borrower, the Lender, Fleet National Bank, as agent, and
certain other Lenders entered into a Revolving Credit and Term Loan Agreement
dated April 14, 2000, as amended (the "Credit Agreement"), providing for loans
from the Lender to the Borrower and have executed certain documentation in
connection therewith (the "Loan Documents");

     WHEREAS, the Lender and the Borrower have agreed to amend certain
provisions of the Revolving Credit Note dated April 14, 2000 made payable by the
Borrower to the Lender (the "Revolving Credit Note"), issued pursuant to the
Credit Agreement as more fully set forth below.

     In consideration of One Dollar ($1.00) and other valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, the Lender and the
Borrower hereby agree as follows:

     1.   AMENDMENT TO REVOLVING CREDIT NOTE. The terms of the Revolving Credit
Note are hereby amended as follows:

          (a)  The amount of "$15,909,090" in the upper left hand corner of page
               1 of the Revolving Credit Note is hereby deleted and replaced
               with "$13,636,365".

          (b)  The amount "$15,909,090" appearing in the twelfth line of the
               first paragraph of page 1 of the Revolving Credit Note is hereby
               deleted and replaced with "$13,636,365".

          (c)  The amount "Fifteen Million Nine Hundred Nine Thousand Ninety
               Dollars ($15,909,090)" appearing in the first and second lines of
               the last paragraph of the Revolving Credit Note is hereby deleted
               and replaced with "Sixteen Million Three Hundred Sixty Three
               Thousand Six Hundred Thirty Five Dollars ($16,363,635)".

     2.   COLLATERAL, ETC. The Loan Documents and the Collateral, as such term
is defined in the Credit Agreement, shall continue to secure the payment of the
Revolving Credit Note, as hereby modified.

     3.   CONTINUING EFFECT. Except as modified herein, the provisions of the
Revolving Credit Note remain in full force and effect in accordance with their
terms, which are hereby ratified and confirmed. All references to the Revolving
Credit Note in the Loan Documents shall be deemed to refer to the Revolving
Credit Note, as amended.

     4.   COUNTERPARTS. This Amendment may be executed in several counterparts
by the Borrower and the Lender, each of which shall be deemed an original but
all of which together shall constitute one and the same Agreement.

<PAGE>   17


Page 2


     Executed as of the date first above written.

                                                     NASHUA CORPORATION


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------



                                   RITTENHOUSE PAPER COMPANY


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      ---------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------



                                   RITTENHOUSE, L.L.C.


/s/ John W. Marchant               By: /s/ John L. Patenaude
--------------------------------      -------------------------------------
Witness                                    John L. Patenaude, Its Duly
                                           --------------------------------
                                           Authorized   V.P. Finance & CFO
                                                     ----------------------

<PAGE>   18

Page 3

     Agreed and consented to:

                                   LASALLE BANK, NATIONAL
                                   ASSOCIATION


                                   By: /s/ Brian Sullivan
--------------------------------      ------------------------------------------
Witness                                    Brian Sullivan, Its Duly
                                           --------------
                                           Authorized  Assistant Vice President
                                                     ---------------------------


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of NASHUA CORPORATION, a Delaware corporation, on behalf of the same.


                                   /s/ Linda J. Madden
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of RITTENHOUSE PAPER COMPANY, an Illinois corporation, on behalf of the
same.


                                   /s/ Linda J. Madden
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal

<PAGE>   19

Page 4


STATE OF NEW HAMPSHIRE
COUNTY OF HILLSBOROUGH

     The foregoing instrument was acknowledged before me this 28th day of
February, 2001, by John Patenaude, the duly authorized Vice President Finance
and CFO of RITTENHOUSE, L.L.C., an Illinois limited liability company, on behalf
of the same.


                                   /s/ Linda J. Madden
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  April 29, 2003
                                   Notary Seal



STATE OF ILLINOIS
COUNTY OF COOK

     The foregoing instrument was acknowledged before me this 14 day of March,
2001, by Brian L. Sullivan, the duly authorized Asst. Vice President, of LaSalle
Bank National Association, a national banking association, on behalf of the
same.


                                   /s/ Effie Dale Scott
                                   ---------------------------------------------
                                   Notary Public
                                   My Commission Expires:  March 24, 2003
                                   Notary Seal