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                                                                    Exhibit 4(a)

                 FOURTH AMENDMENT TO CREDIT AND LOAN AGREEMENT
                 ---------------------------------------------

         THIS FOURTH AMENDMENT (the "Amendment"), effective as of August 24th,
2000, is made to that certain Credit and Loan Agreement, dated as of August 7,
1998, as the same was amended by that certain First Amendment to Credit
Agreement and Loan Agreement, dated as of October 6, 1998, that certain Second
Amendment to Credit and Loan Agreement, dated as of February 9, 1999, and that
certain Third Amendment to Credit and Loan Agreement, dated as of June 23, 2000
(collectively, the "Loan Agreement"), by and among TRANSMATION, INC., an Ohio
corporation (the "Borrower"), THE LENDERS PARTY THERETO FROM TIME TO TIME (the
"Lenders") and KEYBANK NATIONAL ASSOCIATION, a national banking association, as
Agent (in such capacity, together with its successors in such capacity, the
"Agent").

                                   RECITALS:

         WHEREAS, the Borrower has requested that certain changes and
modifications be made to the Loan Agreement, and the Lenders are agreeable to
making the same in accordance with the terms and conditions set forth herein,
commencing as of the effective date first written above.

         NOW, THEREFORE, in consideration of the promises and of the mutual
covenants herein contained, the receipt and sufficiency of which are hereby
mutually acknowledged, and intending to be legally bound hereby, the parties
hereto agree as follows:

         1. DEFINITIONS. All capitalized terms used and not otherwise defined in
this Amendment shall have the meanings ascribed to such terms in the Loan
Agreement,

         2. CERTAIN FINANCIAL COVENANTS.

               (a) Subsection (a) of Section 6.01 of the Loan Agreement is
               amended as follows:

                   (a) (i) for the fiscal quarter ending September 30, 2000
                   permit the Fixed Charge Coverage Ratio (measured as of the
                   period of the four (4) then most recently completed fiscal
                   quarters of the Borrower) to be less than 1.30 to 1.00;

                   (ii) for the fiscal quarter ending December 31, 2000 permit
                   the Fixed Charge Coverage Ratio (measured as of the period of
                   the four (4) then most recently completed fiscal quarters of
                   the Borrower) to be less than 1.40 to 1.00; and

                   (iii) for the fiscal quarter ending March 31, 2001 permit the
                   Fixed Charge Coverage Ratio (measured as of the period of the
                   four (4) then most recently completed fiscal quarters of the
                   Borrower) to be less than 1.45 to 1.00.

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               (b) Subsection (b) of Section 6.01 of the Loan Agreement is
               amended as follows:

                   (b) Permit the consolidated Net Worth of Borrower and its
                   Subsidiaries to be less than the sum of:

                   (i) $12,600,000 by September 30, 2000;

                   (ii) $12,700,000 by December 31, 2000;

                   (iii) $13,100,000 by March 31, 2001.

               (c) Subsection (c) of Section 6.01 of the Loan Agreement is
               amended as follows:

                   (c) Permit the ratio of consolidated Funded Debt of Borrower
                   and its Subsidiaries to the consolidated EBITDA of Borrower
                   and its Subsidiaries, calculated at the same point in time,
                   and measured as of the period of the four (4) then most
                   recently completed fiscal quarters of the Borrower to be:

                   (i) greater than 4.00 to 1.00 from July 1, 2000 to and
                   including September 30, 2000;

                   (ii) greater than 3.65 to 1.00 from October 1, 2000 to and
                   including December 31, 2000;

                   (iv) greater than 3.40 to 1.00 from January 1, 2001 to and
                   including March 31, 2001.

         3. CONDITIONS TO ENTERING INTO AMENDMENT.

         The obligation of each Lender to enter into this Amendment and to make
Loans on the date hereof is subject to the satisfaction of the following
conditions precedent, in addition to the conditions precedent set forth in
Section 4.02 of the Loan Agreement:

         (a) FEES, EXPENSES, ETC. All fees and other compensation to be paid to
         the Agent or the Lenders pursuant hereto, and pursuant to any other
         written agreement on or prior to the date hereof shall have been paid
         or received, and all invoiced expenses incurred by the Agent pursuant
         hereto shall have been paid.

         4. CERTAIN REPRESENTATIONS. Borrower represents and warrants to the
Agent and each Lender as follows:

         (a) All Conditions contained in Section 4.02 of the Loan Agreement have
         been satisfied in all material respects except as otherwise
         specifically set forth herein.

         (b) Borrower's Articles of Incorporation and Code of Regulations
         provided to Agent on August 7, 1998 have not been amended or repealed.

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         5. CERTAIN COVENANTS. The Borrower hereby covenants to the Lenders as
follows:

         (a) Borrower agrees to provide copies of the certificate of
         incorporation or articles of organization and all agreements between it
         and the other shareholders or members of the joint venture it proposes
         to form with Hilton Engineering, Inc., which shall be in form and
         substance satisfactory to Lenders and their counsel. Borrower also
         agrees to pledge at least 66.5% of its capital stock of such entity (or
         of the Borrower's or pledgor's interest in and to such entity, however
         characterized), together with any and all other financing statements,
         stock powers, stock certificates and other documents and instruments
         necessary to create and perfect a valid first priority security
         interest in and to such stock or security.

         6. MISCELLANEOUS. This Amendment is entered into pursuant to and in
accordance with Section 9.03 of the Loan Agreement. This Amendment may be
executed in counterparts, each of which shall be deemed an original and all of
which together shall constitute one and the same instrument. Except as expressly
modified or amended herein, the Loan Agreement and each of the other Loan
Documents to which the Borrower is a party is hereby restated, ratified and
confirmed and shall remain in full force and effect.

         IN WITNESS WHEREOF, the parties hereto, by their officers thereunto
duly authorized, have caused this Fourth Amendment to Credit and Loan Agreement
to be duly executed and delivered as of the date first above written.

                              TRANSMATION, INC.

                              By: /s/ Robert G. Klimasewski
                                  -----------------------------------
                              Name:  Robert G. Klimasewski
                                    ---------------------------------
                              Title: President and CEO
                                     --------------------------------

                              KEYBANK NATIONAL ASSOCIATION,
                              as Agent and a Lender

                              By: /s/ John F. Sorensen, SVP
                                  -----------------------------------
                                  John F. Sorensen, Senior Vice President

                              LENDERS:
                              CITIZENS BANK OF MASSACHUSETTS,
                              F/K/A STATE STREET BANK AND TRUST COMPANY

                              By: /s/ F. Andrew Beise
                                  -----------------------------------
                              Name: F. Andrew Beise
                                    ---------------------------------
                              Title: Senior Vice President
                                     --------------------------------

                                       3<PAGE>   1
                                                                  Exhibit 10(a)

                                 AMENDMENT NO.6
                                     TO THE

                                TRANSMATION, INC.
                             DIRECTORS' STOCK PLAN

                             EFFECTIVE APRIL 1, 2000

         WHEREAS, Transmation, Inc., an Ohio corporation (the "Company"), has
established the Transmation, Inc. Directors' Stock Plan, effective January 17,
1995, as last amended effective November 1, 1997 (the "Plan"); and

         WHEREAS, deeming it appropriate and advisable so to do, and pursuant to
Section 8 of the Plan, the Board of Directors of the Company has authorized,
approved and adopted the further amendment to the Plan set forth herein;

         NOW, THEREFORE, the Plan is hereby further amended, effective April 1,
2000, as follows:

                  1. Section 3(d) of the Plan is hereby amended to provide in
its entirety as follows:

                  "(d) ATTENDANCE AT MEETINGS BY CONFERENCE TELEPHONE.
         Notwithstanding any other provision of this Plan to the contrary: (i) a
         Participating Director who attends by conference telephone equipment
         any regular meeting of the Board shall receive no Award for attendance
         at such meeting; (ii) a Participating Director who attends by
         conference telephone equipment any special meeting of the Board shall
         receive an Award for attendance at such meeting, as if he had been
         present in person, if and to the extent that such Award is otherwise
         payable pursuant to Section 3(b); (iii) a Participating Director who
         attends by conference telephone equipment any meeting of a Committee of
         the Board held on 14 days' or more notice shall receive no Award for
         attendance at such meeting; and (iv) a Participating Director who
         attends by conference telephone equipment any meeting of a Committee of
         the Board held on less than 14 days' notice shall receive an Award for
         attendance at such meeting, as if he had been present in person, if and
         to the extent that such Award is otherwise payable pursuant to Section
         3(b)."

                  2. Except as amended hereby, the Plan shall remain in full
force and effect in accordance with its terms.

         THIS AMENDMENT NO. 6 TO THE TRANSMATION, INC. DIRECTORS' STOCK PLAN WAS
AUTHORIZED, APPROVED AND ADOPTED BY THE BOARD OF DIRECTORS OF THE COMPANY ON
JULY 12, 2000.

                                        /s/ John A. Misiaszek
                                        ----------------------------------
                                        JOHN A. MISIASZEK, SECRETARY

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