Exhibit 4
   FIRSTAR BANK MILWAUKEE, N.A.
   Firstar Financial Services
   Michael A. Hintz,
   Vice President
                              June 25, 1996


   Hein-Werner Corporation
   2120 Pewaukee Road
   Waukesha, WI   53187

   Attn:  Mr. Joseph Dindorf, President

   Gentlemen:

   Please refer to the Revolving Loan and Security Agreement by and between
   Firstar Financial Services, a division of Firstar Bank Milwaukee, N.A.
   ("FFS") and Hein-Werner Corporation, dated October 13, 1993, with
   amendments thereto ("Agreement").  This letter shall serve to further
   amend the Agreement as follows:

   Effective July 1, 1996, the fourth sentence of subsection (a) of Section
   1. LOANS AND SECURITY INTEREST shall be amended to read:

          "The interest rate hereunder shall be computed at an annual rate
          equal to .9 percent plus the rate announced from time to time by
          Lender as its 'prime rate,' which may or may not be the best rate
          available at said bank.  The interest rate shall reduce by 1/4 
          percent in the event Debtor's North American operations show a
          $500,000.090 profit during 1996 (with said reduction effective the
          first day of the month following Lender's receipt of Debtor's
          December 31, 1996 financial statements showing an overall profit)
          and reduce by another 1/4 percent at such time as Massachusetts
          Mutual agrees in writing to defer the first debt installment due
          from Debtor until January, 1998 or the same is otherwise converted
          from debt to equity.  The interest rate shall increase by 1/4
          percent if Debtor's financial statements for the subsequent year
          show a consolidated loss, but shall not be increased above .9
          percent plus the rate announced from time to time by Lender as its
          'prime rate,' which may or may not be the best rate available at
          said bank."

   The second sentence of subsection (a) of Section 9, TERMINATION shall be
   amended to read:

          "While this Agreement is in effect, Debtor agrees to borrow
          funds and pay, at minimum, to Lender the Minimum Monthly
          Charge specified in Section 1. LOANS AND SECURITY
          INTEREST of this Agreement until June 30, 1999, and from year
          to year thereafter, unless Debtor notifies Lender that it does
          not intend to extend the Agreement for another year by giving
          Lender written notice at least ninety (90) days prior to the
          expiration of the then existing term of this Agreement."  

   In all other respects, the Agreement shall remain unchanged and in full
   force and effect.  

   The foregoing amendments are contingent upon the approval of the
   participant in this loan:  Mercantile Business Credit, Inc.

   If the above agrees with your understanding and approval, please indicate
   same by signing the original of this letter and returning it to the
   undersigned.  (NOTE:  If you return executed documents via facsimile, you
   must also return the original executed documents.  You agree FFS may rely
   on facsimile signatures for all purposes and without any liability to
   you.)  If the preconditions (if any) to this amendment are not satisfied
   or if this amendment letter is not executed and returned to FFS on or
   before July 8, 1996, then the proposed amendments herein may be withdrawn
   by FFS by written notice to you.  The amendments set forth herein and any
   accompanying documents will be deemed effective and accepted in Milwaukee,
   Wisconsin, upon our receipt of the executed documents.

                                   Sincerely,


                                   Michael A. Hintz
                                   Division Vice President
   mkf
   Enclosure
   cc:  Nolan H. Zadra

   Agreed to this  28  day of June, 1996.

   HEIN-WERNER CORPORATION

   By:   J. L. Dindorf          
   Title President and C.E.O.

   The undersigned guarantors of the indebtedness of Hein-Werner Corporation
   hereby consent to the foregoing amendments and confirm that their
   guaranties remain in full force and effect.

   BLACKHAWK COLLISION REPAIR, INC.

   By:   J. L. Dindorf         
   Title President and C.E.O.

   HEIN-WERNER OF CANADA, LTD.

   By:   J. L. Dindorf         
   Title President and C.E.O.

   HEIN-WERNER EXPORT CORP.

   By:   J. L. Dindorf         
   Title President and C.E.O.