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                                                                   EXHIBIT 10.28

                                                                  EXECUTION COPY

                               FIRST AMENDMENT TO
                                CREDIT AGREEMENT

     THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this "First Amendment") is made
and entered into as of December 30, 2004, by and among Altra Industrial Motion,
Inc., a Delaware corporation, as Administrative Borrower ("Administrative
Borrower") for the Borrowers (as defined below), the lenders listed on the
signatory page hereof (the "Lenders"), and Wells Fargo Foothill, Inc., a
California corporation, in its capacity as the arranger and administrative agent
for the Lenders ("Agent").

                                   WITNESSETH:

     WHEREAS, each of Administrative Borrower, Warner Electric LLC, a Delaware
limited liability company, Kilian Manufacturing Corporation, a Delaware
corporation, Warner Electric Technology LLC, a Delaware limited liability
company, Formsprag LLC, a Delaware limited liability company, Boston Gear LLC, a
Delaware limited liability company, Nuttall Gear L L C, a Delaware limited
liability company, and Ameridrives International L.P., a Delaware limited
partnership (each, a "Borrower" and, collectively, the "Borrowers"), have
entered into a Credit Agreement dated as of November 30, 2004 (as amended,
restated, supplemented or otherwise modified from time to time, the "Credit
Agreement"), with the Lenders and Agent; and

     WHEREAS, Borrowers, the Lenders and Agent wish to amend the Credit
Agreement, as provided herein;

     NOW, THEREFORE, in consideration of the agreements and provisions herein
contained, the parties hereto do hereby agree as follows:

SECTION 1. DEFINITIONS. Any capitalized terms used but not otherwise defined
herein shall have the meanings ascribed to such terms in the Credit
Agreement.

SECTION 2. AMENDMENT TO CREDIT AGREEMENT. Subject to the satisfaction of the
conditions set forth in Section 4 herein, the Credit Agreement is hereby
amended, effective as of the Effective Date (as defined below), as follows:

     2.01 AMENDMENT TO SECTION 3.6(A). Section 3.6(a) of the Credit Agreement is
hereby amended by replacing the words "30 days" in the first line thereof with
"60 days".

SECTION 3. REPRESENTATIONS AND WARRANTIES. In order to induce Agent and the
Lenders to enter into this First Amendment, Administrative Borrower, for itself
and on behalf of all of the other Borrowers, hereby represents and warrants
that:

     3.01 NO DEFAULT. At and as of the date of this First Amendment, after
giving effect to this First Amendment, no Default or Event of Default has
occurred and is continuing.

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     3.02 REPRESENTATIONS AND WARRANTIES TRUE AND CORRECT. At and as of the date
of this First Amendment, each of the representations and warranties contained in
the Credit Agreement and the other Loan Documents is true and correct in all
material respects (except to the extent that such representations and warranties
relate solely to an earlier date).

     3.03 CORPORATE POWER, ETC. Administrative Borrower (a) has all requisite
corporate power and authority to execute and deliver this First Amendment and to
consummate the transactions contemplated hereby for itself and on behalf of all
of the other Borrowers and (b) has taken all action, corporate or otherwise,
necessary to authorize the execution and delivery of this First Amendment and
the consummation of the transactions contemplated hereby for itself and on
behalf of all of the other Borrowers. Administrative Borrower is entering into
this First Amendment on behalf of all of the other Borrowers in accordance with
Sections 14.1 and 16.9 of the Credit Agreement.

     3.04 NO CONFLICT. The execution, delivery and performance by Administrative
Borrower of this First Amendment will not (a) violate any provision of federal,
state, or local law or regulation applicable to any Borrower, the Governing
Documents of any Borrower, or any order, judgment, or decree of any court or
other Governmental Authority binding on any Borrower, (b) conflict with, result
in a breach of, or constitute (with due notice or lapse of time or both) a
default under any material contractual obligation of any Borrower, (c) result in
or require the creation or imposition of any Lien of any nature whatsoever upon
any properties or assets of any Borrower, other than Permitted Liens, or (d)
require any unobtained approval or consent of any Person under any material
contractual obligation of any Borrower.

     3.05 BINDING EFFECT. This First Amendment has been duly executed and
delivered by Administrative Borrower (on behalf of itself and all of the other
Borrowers) and constitutes the legal, valid and binding obligation of
Administrative Borrower (on behalf of itself and all of the other Borrowers),
enforceable against Administrative Borrower (on behalf of itself and all of the
other Borrowers) in accordance with its terms, except as such enforceability may
be limited by (a) applicable bankruptcy, insolvency, reorganization, moratorium
or other similar laws, now or hereafter in effect, relating to or affecting the
enforcement of creditors' rights generally, and (b) the application of general
principles of equity (regardless of whether such enforceability is considered in
a proceeding in equity or at law).

SECTION 4. CONDITIONS. This First Amendment shall be effective as of December
30, 2004 (the "Effective Date") upon the fulfillment of all of the following
conditions precedent set forth in this Section 4:

     4.01 EXECUTION OF THE FIRST AMENDMENT. Each of the parties hereto shall
have executed and delivered a counterpart of this First Amendment and shall have
delivered (including by way of telefacsimile or electronic mail) the same to
Agent.

     4.02 REPRESENTATIONS AND WARRANTIES. As of the Effective Date, the
representations and warranties set forth in Section 3 hereof shall be true and
correct.


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     4.03 COMPLIANCE WITH TERMS. Borrowers shall have complied in all respects
with the terms hereof and of any other agreement, document, instrument or other
writing to be delivered by Borrowers in connection herewith.

SECTION 5. MISCELLANEOUS.

     5.01 CONTINUING EFFECT. Except as specifically provided herein, the Credit
Agreement and the other Loan Documents shall remain in full force and effect in
accordance with their respective terms and are hereby ratified and confirmed in
all respects.

     5.02 NO WAIVER. This First Amendment is limited as specified and the
execution, delivery and effectiveness of this First Amendment shall not operate
as a modification, acceptance or waiver of any provision of the Credit Agreement
or any other Loan Document, except as specifically set forth herein.

     5.03 REFERENCES.

          (a) From and after the Effective Date, the Credit Agreement, the other
Loan Documents and all agreements, instruments and documents executed and
delivered in connection with any of the foregoing shall each be deemed amended
hereby to the extent necessary, if any, to give effect to the provisions of this
First Amendment.

          (b) From and after the Effective Date, (i) all references in the
Credit Agreement to "this Agreement", "hereto", "hereof", "hereunder" or words
of like import referring to the Credit Agreement shall mean the Credit Agreement
as amended hereby and (ii) all references in the Credit Agreement, the other
Loan Documents or any other agreement, instrument or document executed and
delivered in connection therewith to "Credit Agreement", "thereto", "thereof",
"thereunder" or words of like import referring to the Credit Agreement shall
mean the Credit Agreement as amended hereby.

     5.04 GOVERNING LAW. THIS FIRST AMENDMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

     5.05 SEVERABILITY. The provisions of this First Amendment are severable,
and if any clause or provision shall be held invalid or unenforceable in whole
or in part in any jurisdiction, then such invalidity or unenforceability shall
affect only such clause or provision, or part thereof, in such jurisdiction and
shall not in any manner affect such clause or provision in any other
jurisdiction, or any other clause or provision in this First Amendment in any
jurisdiction.

     5.06 COUNTERPARTS. This First Amendment may be executed in any number of
counterparts, each of which counterparts when executed and delivered shall be an
original, but all of which shall together constitute one and the same
instrument. Delivery of an executed counterpart of this First Amendment by
telefacsimile or electronic mail shall be equally effective as delivery of a
manually executed counterpart. A complete set of counterparts shall be lodged
with Administrative Borrower and Agent.


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     5.07 HEADINGS. Section headings in this First Amendment are included herein
for convenience of reference only and shall not constitute a part of this First
Amendment for any other purpose.

     5.08 BINDING EFFECT; ASSIGNMENT. This First Amendment shall be binding upon
and inure to the benefit of Borrowers, the Lenders and Agent and their
respective successors and assigns; provided, however, that the rights and
obligations of Borrowers under this First Amendment shall not be assigned or
delegated without the prior written consent of Agent.

     5.09 EXPENSES. Borrowers agree to pay Agent for all reasonable expenses,
including reasonable fees of attorneys and paralegals for Agent, incurred by
Agent in connection with the preparation, negotiation and execution of this
First Amendment and any document required to be furnished herewith pursuant to
the terms of the Credit Agreement and the Fee Letter.

                           [Signature page to follow]


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     IN WITNESS WHEREOF, the parties hereto have caused this First Amendment to
be executed by their respective officers thereunto duly authorized, as of the
date first above written.

                                        ALTRA INDUSTRIAL MOTION, INC.,
                                        a Delaware corporation, as
                                        Administrative Borrower on behalf
                                        of itself and all other Borrowers


                                        By: /s/ Thomas Tatarczuch
                                            ------------------------------------
                                        Name: Thomas Tatarczuch
                                        Title: Chief Financial Officer


                                        WELLS FARGO FOOTHILL, INC.,
                                        a California corporation, as Agent and
                                        Lender


                                        By: /s/ John T. Leonard
                                            ------------------------------------
                                        Name: John T. Leonard
                                        Title: Vice President