<PAGE>
                                                                 EXHIBIT 10.14.6

                                                                  Execution Copy

        SIXTH AMENDMENT TO CREDIT AGREEMENT AND LIMITED WAIVER OF DEFAULT

         This SIXTH AMENDMENT TO CREDIT AGREEMENT AND LIMITED WAIVER OF DEFAULT
(this "Amendment"), made and entered into as of March 25, 2003, is by and
between RTW, Inc., a Minnesota corporation (the "Borrower"), and U.S. Bank
National Association, a national banking association (the "Bank").

                                    RECITALS

         1. The Bank and the Borrower entered into a Credit Agreement dated as
of March 31, 2000 as amended by a First Amendment dated as of May 4, 2000, a
Second Amendment dated as of March 28, 2001, a Third Amendment dated as of
September 29, 2001, a Fourth Amendment and Limited Waiver of Default dated as of
March 22, 2002 and a Fifth Amendment dated as of December 17, 2002 (as amended,
the "Credit Agreement"); and

         2. The Borrower desires to amend certain provisions of the Credit
Agreement, and the Bank has agreed to make such amendments, subject to the terms
and conditions set forth in this Amendment.

                                    AGREEMENT

         NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, the parties hereto hereby covenant
and agree to be bound as follows:

         Section 1. Capitalized Terms. Capitalized terms used herein and not
otherwise defined herein shall have the meanings assigned to them in the Credit
Agreement, unless the context shall otherwise require.

         Section 2. Amendments. The Credit Agreement is hereby amended as
follows:

                  2.1 Term Note. Exhibit 1.1(B) to the Credit Agreement is
         hereby amended in its entirety to read as set forth in Exhibit A to
         this Amendment, which is made a part of the Credit Agreement as Exhibit
         1.1(B) thereto.

         Section 3. Effectiveness of Amendments. The amendments contained in
this Amendment shall become effective upon delivery by the Borrower of, and
compliance by the Borrower with, the following:

                  3.1 This Amendment and the Fourth Amended and Restated Term
         Note in the form of Exhibit A hereto (the "Note"), each duly executed
         by the Borrower.

                  3.2 A copy of the resolutions of the Board of Directors of the
         Borrower authorizing the execution, delivery and performance of this
         Amendment and Note certified as true and accurate by its Secretary or
         Assistant Secretary, along with a




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         certification by such Secretary or Assistant Secretary (i) certifying
         that there has been no amendment to the Articles of Incorporation or
         Bylaws of the Borrower since true and accurate copies of the same were
         delivered to the Bank with a certificate of the Secretary of the
         Borrower dated March 31, 2000, except for an amendment to the Articles
         of Incorporation dated November 7, 2002 allowing for a reverse split of
         the Borrower's common stock, a true and correct certified copy of which
         has been delivered by the Secretary of the Borrower, and (ii)
         identifying each officer of the Borrower authorized to execute this
         Amendment, the Note and any other instrument or agreement executed by
         the Borrower in connection with this Amendment (collectively, the
         "Amendment Documents"), and certifying as to specimens of such
         officer's signature and such officer's incumbency in such offices as
         such officer holds.

                  3.3 The Borrower shall have satisfied such other conditions as
         specified by the Bank, including payment of all unpaid legal fees and
         expenses incurred by the Bank through the date of this Amendment in
         connection with the Credit Agreement and the Amendment Documents.

         Section 4. Defaults and Waivers.

                  4.1 Events of Default and Unmatured Events of Default.

                  (a) Minimum EBIT. Under Section 6.17 of the Credit Agreement,
         the Borrower agreed not to permit its annualized EBIT, as of December
         31, 2002, to be less than $4,000,000. As of December 31, 2002, the
         Borrower's annualized EBIT was less than $4,000,000. As a result, an
         Event of Default has occurred under Section 7.1(c) of the Credit
         Agreement.

                  4.2 Waiver. Upon the date on which this Amendment becomes
         effective, the Bank hereby waives the Borrower's Default and Event of
         Default described in the preceding Section 4.1(a) (the "Existing
         Default"). The waiver of the Existing Default set forth above is
         limited to the express terms thereof, and nothing herein shall be
         deemed a waiver by the Bank of any other term, condition,
         representation or covenant applicable to the Borrower under the Credit
         Agreement (including but not limited to any future occurrence similar
         to the Existing Default) or any of the other agreements, documents or
         instruments executed and delivered in connection therewith, or of the
         covenants described therein. The waiver set forth herein shall not
         constitute a waiver by the Bank of any other Default or Event of
         Default, if any, under the Credit Agreement, and shall not be, and
         shall not be deemed to be, a course of action with respect thereto upon
         which the Borrower may rely in the future, and the Borrower hereby
         expressly waives any claim to such effect.

         Section 5. Representations, Warranties, Authority, No Adverse Claim.

                  5.1 Reassertion of Representations and Warranties, No Default.
         The Borrower hereby represents that on and as of the date hereof and
         after giving effect to this Amendment (a) all of the representations
         and warranties contained in the Credit Agreement are true, correct and
         complete in all respects as of the date hereof as though





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         made on and as of such date, except for changes permitted by the terms
         of the Credit Agreement, and (b) there will exist no Default or Event
         of Default under the Credit Agreement as amended by this Amendment on
         such date which has not been waived by the Bank.

                  5.2 Authority, No Conflict, No Consent Required. The Borrower
         represents and warrants that the Borrower has the power and legal right
         and authority to enter into the Amendment Documents and has duly
         authorized as appropriate the execution and delivery of the Amendment
         Documents and other agreements and documents executed and delivered by
         the Borrower in connection herewith or therewith by proper corporate
         action, and none of the Amendment Documents nor the agreements
         contained herein or therein contravenes or constitutes a default under
         any agreement, instrument or indenture to which the Borrower is a party
         or a signatory or a provision of the Borrower's Articles of
         Incorporation, Bylaws or any other agreement or requirement of law, or
         result in the imposition of any Lien on any of its property under any
         agreement binding on or applicable to the Borrower or any of its
         property except, if any, in favor of the Bank. The Borrower represents
         and warrants that no consent, approval or authorization of or
         registration or declaration with any Person, including but not limited
         to any governmental authority, is required in connection with the
         execution and delivery by the Borrower of the Amendment Documents or
         other agreements and documents executed and delivered by the Borrower
         in connection therewith or the performance of obligations of the
         Borrower therein described, except for those which the Borrower has
         obtained or provided and as to which the Borrower has delivered
         certified copies of documents evidencing each such action to the Bank.

                  5.3 No Adverse Claim. The Borrower warrants, acknowledges and
         agrees that no events have been taken place and no circumstances exist
         at the date hereof which would give the Borrower a basis to assert a
         defense, offset or counterclaim to any claim of the Bank with respect
         to the Obligations.

         Section 6. Affirmation of Credit Agreement, Further References,
Affirmation of Security Interest. The Bank and the Borrower each acknowledge and
affirm that the Credit Agreement, as hereby amended, is hereby ratified and
confirmed in all respects and all terms, conditions and provisions of the Credit
Agreement, except as amended by this Amendment, shall remain unmodified and in
full force and effect. All references in any document or instrument to the
Credit Agreement are hereby amended and shall refer to the Credit Agreement as
amended by this Amendment. The Borrower confirms to the Bank that the
Obligations are and continue to be secured by the security interest granted by
the Borrower in favor of the Bank under the Security Documents, and all of the
terms, conditions, provisions, agreements, requirements, promises, obligations,
duties, covenants and representations of the Borrower under such documents and
any and all other documents and agreements entered into with respect to the
obligations under the Credit Agreement are incorporated herein by reference and
are hereby ratified and affirmed in all respects by the Borrower.

         Section 7. Merger and Integration, Superseding Effect. This Amendment,
from and after the date hereof, embodies the entire agreement and understanding
between the parties hereto and supersedes and has merged into this Amendment all
prior oral and written agreements





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on the same subjects by and between the parties hereto with the effect that this
Amendment, shall control with respect to the specific subjects hereof and
thereof.

         Section 8. Severability. Whenever possible, each provision of this
Amendment and the other Amendment Documents and any other statement, instrument
or transaction contemplated hereby or thereby or relating hereto or thereto
shall be interpreted in such manner as to be effective, valid and enforceable
under the applicable law of any jurisdiction, but, if any provision of this
Amendment, the other Amendment Documents or any other statement, instrument or
transaction contemplated hereby or thereby or relating hereto or thereto shall
be held to be prohibited, invalid or unenforceable under the applicable law,
such provision shall be ineffective in such jurisdiction only to the extent of
such prohibition, invalidity or unenforceability, without invalidating or
rendering unenforceable the remainder of such provision or the remaining
provisions of this Amendment, the other Amendment Documents or any other
statement, instrument or transaction contemplated hereby or thereby or relating
hereto or thereto in such jurisdiction, or affecting the effectiveness, validity
or enforceability of such provision in any other jurisdiction.

         Section 9. Successors. The Amendment Documents shall be binding upon
the Borrower and the Bank and their respective successors and assigns, and shall
inure to the benefit of the Borrower and the Bank and the successors and assigns
of the Bank.

         Section 10. Legal Expenses. As provided in Section 8.2 of the Credit
Agreement, the Borrower agrees to reimburse the Bank, upon execution of this
Amendment, for all reasonable out-of-pocket expenses (including attorneys' fees
and legal expenses of Dorsey & Whitney LLP, counsel for the Bank) incurred in
connection with the Credit Agreement, including in connection with the
negotiation, preparation and execution of the Amendment Documents and all other
documents negotiated, prepared and executed in connection with the Amendment
Documents, and in enforcing the obligations of the Borrower under the Amendment
Documents, and to pay and save the Bank harmless from all liability for, any
stamp or other taxes which may be payable with respect to the execution or
delivery of the Amendment Documents, which obligations of the Borrower shall
survive any termination of the Credit Agreement.

         Section 11. Headings. The headings of various sections of this
Amendment have been inserted for reference only and shall not be deemed to be a
part of this Amendment.

         Section 12. Counterparts. The Amendment Documents may be executed in
several counterparts as deemed necessary or convenient, each of which, when so
executed, shall be deemed an original, provided that all such counterparts shall
be regarded as one and the same document, and either party to the Amendment
Documents may execute any such agreement by executing a counterpart of such
agreement.

         Section 13. Governing Law. THE AMENDMENT DOCUMENTS SHALL BE GOVERNED BY
THE INTERNAL LAWS OF THE STATE OF MINNESOTA, WITHOUT GIVING EFFECT TO CONFLICT
OF LAW PRINCIPLES THEREOF, BUT GIVING EFFECT TO FEDERAL LAWS APPLICABLE TO
NATIONAL BANKS, THEIR HOLDING COMPANIES AND THEIR AFFILIATES.






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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed as of the date and year first above written.

BORROWER:                   RTW, INC.



                            By:      /s/ Jeffrey B. Murphy
                                ------------------------------------------------

                            Title:   Chief Financial Officer
                                   ---------------------------------------------


BANK:                       U.S. BANK NATIONAL ASSOCIATION



                            By:      /s/ Christine J. Geer
                                ------------------------------------------------

                            Title:   Corporate Banking Officer
                                   ---------------------------------------------













                       [Signature Page to Sixth Amendment]

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                                                                    EXHIBIT A TO
                                                              SIXTH AMENDMENT TO
                                                                CREDIT AGREEMENT

                                                               EXHIBIT 1.1(B) TO
                                                                CREDIT AGREEMENT


                      FOURTH AMENDED AND RESTATED TERM NOTE

$1,000,000                                                        March 25, 2003
                                                          Minneapolis, Minnesota

         FOR VALUE RECEIVED, RTW, INC., a corporation organized under the laws
         of the State of Minnesota, hereby promises to pay to the order of U.S.
         BANK NATIONAL ASSOCIATION (the "Bank") at its main office in
         Minneapolis, Minnesota, in lawful money of the United States of America
         in Immediately Available Funds (as such term and each other capitalized
         term used herein are defined in the Credit Agreement hereinafter
         referred to) on the Term Maturity Date, the principal amount of ONE
         MILLION AND NO/100 DOLLARS ($1,000,000), and to pay interest (computed
         on the basis of actual days elapsed and a year of 360 days) in like
         funds on the unpaid principal amount hereof from time to time
         outstanding at the rates and times set forth in the Credit Agreement.

         The principal of this note shall be payable in installments in the
         following amounts on the following dates:

<TABLE>
<CAPTION>
                  ----------------------------------------- --------------------------------------
                  Date                                      Installment
                  ----------------------------------------- --------------------------------------
                  <S>                                       <C>
                  June 30, 2003                             $250,000
                  ----------------------------------------- --------------------------------------
                  September 30, 2003                        $350,000
                  ----------------------------------------- --------------------------------------
                  December 31, 2003                         $400,000
                  ----------------------------------------- --------------------------------------
                  Term Maturity Date                        All remaining principal, plus
                                                            accrued and unpaid interest
                  ----------------------------------------- --------------------------------------
</TABLE>

         This note is the Term Note referred to in the Credit Agreement dated as
         of March 31, 2000 (as the same has been and may hereafter be from time
         to time amended, restated or otherwise modified, the "Credit
         Agreement") between the undersigned and the Bank. This note is secured
         and its maturity is subject to acceleration, in each case upon the
         terms provided in said Credit Agreement.

         This note amends and restates in its entirety an existing promissory
         note dated March 22, 2002 in the original principal amount of
         $3,500,000 issued by RTW, Inc. to the order of the Bank (the "Prior
         Note"). It is expressly intended, understood and agreed that all




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         amounts outstanding under said Prior Note as of the date hereof shall
         be considered outstanding hereunder from and after the date hereof and
         shall not be considered paid (nor shall the undersigned's obligation to
         pay the same be considered discharged or satisfied) as a result of the
         issuance of this note.

         In the event of default hereunder, the undersigned agrees to pay all
         costs and expenses of collection, including reasonable attorneys' fees.
         The undersigned waives demand, presentment, notice of nonpayment,
         protest, notice of protest and notice of dishonor.

         THE VALIDITY, CONSTRUCTION AND ENFORCEABILITY OF THIS NOTE SHALL BE
         GOVERNED BY THE INTERNAL LAWS OF THE STATE OF MINNESOTA WITHOUT GIVING
         EFFECT TO THE CONFLICT OF LAWS PRINCIPLES THEREOF, BUT GIVING EFFECT TO
         FEDERAL LAWS OF THE UNITED STATES APPLICABLE TO NATIONAL BANKS.

                             RTW, INC.


                             By       /s/ Jeffrey B. Murphy
                                 -------------------------------------------
                             Title    Chief Financial Officer
                                    ----------------------------------------