Document:

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                                                                   Exhibit 4.9.1

                                AMENDMENT NO. 1
               TO SECOND AMENDED AND RESTATED SECURITY AGREEMENT

     This AMENDMENT No. 1 (the "Amendment") effective as of September 30, 2000
is made to that certain Second Amended and Restated Security Agreement dated
June 30, 1999 as heretofore amended March 17, 2000 and as may be amended from
time to time (the "Loan Agreement"), by and between AEROVOX INCORPORATED, a
Delaware corporation with a chief executive office at 167 John Vertente
Boulevard, New Bedford, Massachusetts (the "Borrower"), and FLEET CAPITAL
CORPORATION, as successor to BANKBOSTON, N.A., a national banking association
with a banking office at One Hundred Federal Street, Boston, Massachusetts (the
"Lender").

     Each of the capitalized terms which are used herein without definition and
which are defined in the Security Agreement referred to above shall have the
same meaning herein as in the Security Agreement, as amended hereby.

                                   RECITALS
                                   --------

     The Borrower and the Lender are parties to the Loan Agreement.  In
connection with certain amendments to the financing arrangements between the
Borrower and the Lender as provided in Amendment No. 2 to the Second Amended and
Restated Loan Agreement dated June 30, 1999 the Borrower and the Lender wish to
amend the Security Agreement to expand the security interest granted therein to
include equipment and other goods in addition to the security interest in other
tangible and intangible personal property previously granted to the Lender.

                                   AMENDMENT
                                   ---------

NOW, THEREFORE, in consideration of the foregoing premises, the parties hereto
hereby agree as follows:

1. (S)1._Of the Security Agreement is hereby amended to add the words;
   "equipment, fixtures and other goods (as defined in the Uniform Commercial
   Code)" immediately after the parentheses and immediately before the words
   "chattel paper" in the fifth line of such (S)1.

2. Fleet Capital Corporation is hereby substituted for BankBoston, N.A. as
   secured party under the Security Agreement and the word "Lender" shall
   replace the word "Bank" wherever the word Bank appears in the Security
   Agreement.

3. The Borrower shall cooperate with the Lender in executing and delivering to
   the Lender UCC-1 and UCC-3 financing statements as required by the Lender to
   indicate assignment of the security interest in the Collateral to the Lender
   and to expand the definition of Collateral as provided in paragraph 1 hereof.
<PAGE>

                                                                   Exhibit 4.9.1

4. This Amendment No. 1 may be executed in any number of counterparts, but all
   such counterparts shall together constitute but one integrated instrument. In
   making proof of this Amendment No. 1, it shall not be necessary to produce or
   account for more than one counterpart signed by each party hereto by and
   against which enforcement hereof is sought.

5. This Amendment No. 1 shall be construed according to an governed by the laws
   of the Commonwealth of Massachusetts.

                                      AEROVOX INCORPORATED

                                      By:    F. Randal Hunt
                                      Title: Sr. Vice President Finance and CFO

The within Amendment is hereby agreed and accepted.

                                      FLEET CAPITAL CORPORATION, as successor to
                                      BANKBOSTON, N.A.

                                      By:    Ruben V. Klein
                                      Title: Vice President<PAGE>

                                                                    Exhibit 4.10

                                                               NOTE PAYABLE WITH
                                                         FIXED DUE DATE AND RATE
                                                       WITH INTEREST PAYMENTS AT
                                                          DUE DATE IN US DOLLARS

                                       CHECKING ACCOUNT IN DOLLARS No. 010263451

SUBSCRIPTION DATE:  NOVEMBER 21/st/ 2000

PLACE OF SUBSCRIPTION: Mexico City

                          U.S.D  $1,000,000.00 Dollars

The subscribed AEROVOX DE MECIO S.A. DE C.V. (The "Subscriptor"), a merchantile
society duly constituted and existing in accordance to the laws of the United
Mexican States (Mexico), promises unconditionally through this NOTE PAYABLE to
pay to the order of BANCO BILBAO VIZCAYA - MEVICO S.A. INSTITUCION DE BANCA
MULTIPLE, GRUPO FINANCIERO BBV - PROBUSRA) (The "Bank"), the principal amount of
U.S. $1,000,000.00 (ONE MILLION DOLLARS 00/100) legal currency of the United
States of America ("Dollars"), precisely through one amortization demandable and
payable on MAY 18/th/, 2001  (Date of the Final Payment).

The Subscriptor promises to pay precisely on the Date of Final Payment, the
interests on the unpaid principal amount of this NOTE PAYABLE, such that will
draw form the date of subscription of this NOTE PAYABLE and until the Date of
Final Payment, at an annual interest rate of 9.30% (NINE POINT THIRTY PERCENT)

In the case that the Subscriptor does not pay on the date of presentation of
this NOTE PAYABLE the total amount of this NOTE PAYABLE , the Subscriptor will
pay moratory interests on the unpaid and past due amount, counting from the day
following the due date until the total payment, at an interest rate equal to the
multiplication by three (3) of the ordinary interest rate referred in the above
paragraph.

The interests referred to in this NOTE PAYABLE will be counted on the base of a
360 (three hundred and sixty) days year and by the number of calendar days
elapsed, including the first day but excluding the last of such days.
<PAGE>

                                                                    Exhibit 4.10

All payments related to this NOTE PAYABLE will be made by the Subscriptor in
favor of the Bank. In the city of Concord, California, United States of America,
to account No. 62__-692210 ABA # 121000358 SWIFT BOFAUS6SXXX that the Bank keeps
with Bank of America NT & SA, in 1850 Gateway Blvd. Concord, CA 94520, in the
City of Concord, California , no later that 11:00 AM (Concord, California time)
on the date that such paymenst must be made, in Dollars and in freely
transferrable funds and available same day, or in any other account notified in
writing by the Bank and with enough anticipation to instruct the Subscriptor.
The Subscriptor agrees to make all the payments relating to the principal and
interests of this NOTE PAYABLE, free and without deductions for any current or
future fiscal responsibility with respect to such concepts payable in any
jurisdiction.

In all the cases when a payment  is due according to this NOTE PAYABLE, or when
any Interest Period ends in a non Working Day (according to the definition
below), such paymentmust be made, or such Interest Period will end on the
following Working Day.

As used in the NOTE PAYABLE, the following terms will have the following
meanings:

"Working Day"  means any day of the year in wich Dollar operations take place in
 -------------
the Interbank market of London and on which the banks of the city of London,
England, are open to the public to do Dollar operations, and on which the banks
in the city of Concord , California , are not authorized or abligated to close.

The Subscriber and each one of the indorsers (if any) are subject irrevocably to
the jurisdictions of the competent Courts of the State of California, United
States of America, or in the Federal Courts located in the city of Concord,
California, and in the competent Courts of United Mexican States, with residence
in Mexico City, at the Bank's choice, in any action or procedure arising or
relative to this NOTE PAYABLE.  The Subscriptor and the indorsers (if any)
irrevocably waive any other jurisdiction to which they may have right due to
their current or future address, or in any other way; in the same manner they
irrevocably waive, in the measure they can do it, to operate the defense of not
convenient territorial jurisdiction with any action or legal procedure relative
to this NOTE PAYABLE in any of the Courts mentioned before.
<PAGE>

                                                                    Exhibit 4.10

This NOTE PAYABLE will be ruled and interpreted according to the laws of Mexico;
in intelligence, however, that any legal action or procedure (with the exception
of an action to demand the compliance of a sentence obtained in other
jurisdiction) by the Bank or the holder of this NOTE PAYABLE in the Courts of
the competent jurisdiction of Concord, California, United States of America,
this NOTE PAYABLE  will be considered an instrument made in agreement with the
laws of the State of California and for such effect will rule and interpret
itself according to the laws of the State of California.

This NOTE PAYABLE has three pages.

Subscritor

                                                  ADDRESS
AEROVOX MEXICO S.A. DE C.V.                       AV. TEZOZOMOC 239
REPRESENTED BY:                                   FRACC. IND SAN ANTONIO
                                                  MEX, D.F.

/s/ ENRIQUE SANCHEZ ALDUNATE
----------------------------<PAGE>

                                                                Exhibit 4.23

                            STOCK OPTION AGREEMENT
                            ----------------------

     THIS STOCK OPTION AGREEMENT made as of the 1st day of December, 2000, by
and between CAIS INTERNET, INC. (hereinafter referred to as "CAIS Internet"),
and Wendell S. Nye (hereinafter referred to as the "Employee").

The parties hereto agree as follows:

     1.  Stock Option.
         -------------

          CAIS Internet hereby grants Employee an option to purchase (the
"Option") all or any part of a total of One Hundred Five Thousand (105,000)
shares of CAIS Internet's Common Stock (the "Option Shares") upon the terms and
conditions set forth herein.  The purchase price of the Option Shares which
Employee elects to purchase under this Agreement shall be $3.00 per share.
                                                          ------
Employee shall, upon delivery to him of any Option Shares that he elects to
purchase hereunder, pay CAIS Internet the full purchase price for such Option
Shares on the date of exercise. The Option is exercisable in whole or in part
with respect to Option Shares by written notice to CAIS Internet at any time
after the date hereof for five years. The Options are fully vested and
exercisable as of the date hereof.

     2.  Registration Rights.
         -------------------

          On and as of each of June 1, 2001, December 1, 2001, June 1, 2002 and
December 1, 2002, the Employee will be entitled to piggy-back registration
rights of 25% of the Option Shares as follows:  on and as of each such date, the
Employee is entitled to one right to piggy-back on any registration statement
initiated by CAIS Internet for a offering of its Common Stock (other than in
connection with a stock plan, corporate reorganization or Rule 145 transaction)
with respect to the Common Stock issuable upon exercise of the Option Shares, on
customary terms and subject to the terms of the underwriting of such offering,
the prior rights, if any, of other stockholders of the CAIS Internet and the
CAIS Internet's right to terminate the offering at any time.

     3.  Non-Assignability.
         -----------------

          The Employee shall have no right to assign this Agreement, or any of
his or her rights or obligations hereunder, to another party or parties.  The
Option granted hereunder is not assignable by operation of law or subject to
execution, attachment or similar process. CAIS Internet shall have the right to
assign this Agreement to any successor entity provided that such entity agrees
to assume all of CAIS Internet's obligations hereunder.

     4.  Law Applicable.
         ---------------

          This Agreement shall be construed in accordance with the laws of the
District of Columbia.

                                       1
<PAGE>

     5.  Adjustment Provisions.
         ---------------------

          The number of shares of Common Stock subject to the Option and the
exercise price shall be adjusted in accordance with generally accepted
accounting principles in the event of a stock dividend, stock split, stock
distribution, reverse split or other combination of shares, recapitalization or
otherwise, which affects the Common Stock.

     6.  Entire Agreement.
         -----------------

          This instrument contains all of the agreements and understandings
between the parties hereto with respect to the stock options granted by CAIS
Internet to Employee hereunder, and no oral agreements or written correspondence
shall be held to affect the provisions hereof and shall be binding upon CAIS
Internet's successors and assigns.  All subsequent changes and modifications,
to be valid, shall be by written instrument executed by CAIS Internet and the
Employee.

     IN WITNESS WHEREOF, CAIS Internet has caused this Agreement to be executed
on its behalf by its duly authorized officers and the Employee has hereunto set
his hand, all done on the day and in the year first hereinabove written.

                                 CAIS INTERNET, INC.

                                 By:_________________________
                                 Name:
                                 Title:

                                 EMPLOYEE:
                                 --------

                                 ___________________________
                                 Wendell S. Nye

                                       2

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