<PAGE>   1
                                                                   Exhibit 10.77

                          OUTSOURCE FUNDING CORPORATION

                                 TENTH AMENDMENT
                                       TO
                           REVOLVING CREDIT AGREEMENT

         This Tenth Amendment (this "Amendment"), dated as of July 31, 2000,
among (a) OUTSOURCE FUNDING CORPORATION; (b) each of the banks party to the
Credit Agreement hereinafter referred to (collectively, the "Banks") and (c)
FLEET NATIONAL BANK (f/k/a BankBoston, N.A.), as agent for the Banks (the
"Agent"), pursuant to that certain Revolving Credit Agreement (as amended and in
effect from time to time, the "Credit Agreement"), dated as of October 1, 1999,
among the Borrower, the Banks and the Agent. Capitalized terms used herein and
which are not otherwise defined shall have the respective meanings ascribed
thereto in the Credit Agreement.

         WHEREAS, the Borrower has requested that the Banks and the Agent agree
to amend the terms of the Credit Agreement in certain respects; and

         WHEREAS, the Banks and the Agent are willing to amend the terms of the
Credit Agreement in such respects, upon the terms and subject to the conditions
contained herein; and

         NOW, THEREFORE, in consideration of the mutual agreements contained in
the Credit Agreement herein and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

         ss.1.    AMENDMENT TO DEFINITIONS. Section 1.1 of the Credit Agreement
is hereby amended by deleting the words "July 31, 2000" appearing in the
definition of "Revolving Credit Loan Maturity Date" and substituting in lieu
thereof the words "August 15, 2000".

         ss.2.    CONFIRMATION OF OBLIGATIONS. The Borrower hereby confirms that
the obligations of the Borrower arising under each of the Loan Documents to
which it is a party, including Indebtedness consisting of Loans, are included in
the Obligations, are not subject to any claims or defenses whatsoever, and
constitute valid and binding obligations of the Borrower enforceable against the
Borrower in accordance with its terms, except as enforceability may be limited
by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting the enforcement of creditors' rights generally and by general
equitable principles (whether enforcement is sought by proceedings in equity or
at law).

         ss.3.    RELEASE. The Borrower, on the Borrower's own behalf and on
behalf of the Borrower's successors and assigns, hereby waives, releases and
discharges the Agent and each Bank and all of the affiliates of the Agent and
each Bank, and all of the directors, officers, employees, attorneys and agents
of the Agent, each Bank and such affiliates, from any and all claims, demands,
actions or causes of action (known and unknown) arising out of or in any way
relating to the Loan Documents and any

<PAGE>   2
                                      -2-


documents, agreements, dealings or other matters connected with the Credit
Agreement, in each case to the extent arising (x) on or prior to the date hereof
or (y) out of, or relating to, actions, dealings or matters occurring on or
prior to the date hereof. The waivers, releases, and discharges in this Section
3 shall be effective regardless of whether the conditions to this Amendment are
satisfied and regardless of any other event that may occur or not occur after
the date hereof.

         ss.4.    REPRESENTATIONS AND WARRANTIES. The Borrower represents and
warrants to the Banks and the Agents as follows:

         (a)      Representations and Warranties in Credit Agreement. The
representations and warranties of the Borrower contained in the Credit
Agreement, as amended hereby, (a) were true and correct in all material respects
when made, and (b) except (i) as a result of changes in the ordinary course of
business permitted under the Credit Agreement and (ii) to the extent such
representations and warranties by their terms are made solely as of a prior
date, continue to be true and correct in all material respects on the date
hereof.

         (b)      Authority, Etc. The execution and delivery by the Borrower of
this Amendment and the performance by the Borrower of all of their agreements
and obligations under this Amendment and the Credit Agreement as amended hereby
(i) are within the corporate authority of the Borrower, (ii) have been duly
authorized by all necessary corporate or other proceedings or actions, as the
case may be, by the Borrower, (iii) do not conflict with or result in any breach
or contravention of any provision of law, statute, rule or regulation to which
the Borrower is subject or any judgment, order, writ, injunction, license or
permit applicable to the Borrower, and (iv) do not conflict with any provision
of the corporate charter, by-laws or partnership agreement of, or any agreement
or other instrument binding upon, the Borrower.

         (c)      Enforceability of Obligations. This Amendment, the Credit
Agreement as amended hereby, and the other Loan Documents constitute the legal,
valid and binding obligations of the Borrower enforceable against the Borrower
in accordance with their respective terms, except as enforceability may be
limited by applicable bankruptcy, insolvency, reorganization, moratorium or
similar laws affecting the enforcement of creditors' rights generally and by
general equitable principles (whether enforcement is sought by proceedings in
equity or at law). After giving effect to this Amendment, no Default or Event of
Default exists under the Credit Agreement.

         ss.5.    CONDITIONS TO EFFECTIVENESS. This Amendment shall be effective
as of the date hereof upon the satisfaction of the following conditions
precedent:

         (a)      receipt by the Agent of an original counterpart signature to
this Amendment, duly executed and delivered by the Borrower, the Banks and the
Agent;

         (b)      receipt by the Agent of evidence satisfactory to the Agent
that the OI Revolving Credit Agreement termination date has been extended until
August 15, 2000 from its current July 31, 2000 maturity date;

<PAGE>   3
                                      -3-


         (c)      payment by the Borrower of the legal, appraisal, consultant
and out-of-pocket fees and expenses of the Agent, in each case, to the extent
that invoices for the same have been presented to the Borrower; and

         (d)      payment by the Borrower of all fees and expenses of
Nightingale & Associates, LLC and any other consultant retained by the Agent
and/or the Banks in connection with consulting services, to the extent that
invoices for the same have been presented to the Borrower (in addition to any
amount previously paid as a retainer to such consultant).

         ss.6.    MISCELLANEOUS PROVISIONS. (a) Except as otherwise expressly
provided by this Amendment, all of the terms, conditions and provisions of the
Credit Agreement shall remain the same. It is declared and agreed by each of the
parties hereto that the Credit Agreement, as amended hereby, shall continue in
full force and effect, and that this Amendment and the Credit Agreement shall be
read and construed as one instrument.

         (b)      THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED ACCORDING
TO, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS (EXCLUDING THE LAWS APPLICABLE
TO CONFLICTS OR CHOICE OF LAW).

         (c)      This Amendment may be executed in any number of counterparts,
but all such counterparts shall together constitute but one instrument. In
making proof of this Amendment 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.

         (d)      Headings or captions used in this Amendment are for
convenience of reference only and shall not define or limit the provisions
hereof.

         (e)      The Borrower hereby agrees to pay to the Agent, on demand by
the Agent, all reasonable out-of-pocket costs and expenses incurred or sustained
by the Agent in connection with the preparation of this Amendment (including
without limitation, recording and filing fees, notarization fees, stamp taxes,
any other tax imposed by reason of the execution and delivery of the Loan
Documents, the reasonable fees and expenses of counsel to the Agent and the
reasonable fees and expenses of the Agent's commercial finance examiners and
commercial auditors).

<PAGE>   4


         IN WITNESS WHEREOF, each of the undersigned has duly executed this
Amendment as of the date first set forth above.

                           OUTSOURCE FUNDING CORPORATION


                           By: /s/ Scott R. Francis
                              --------------------------
                              Name:  Scott R. Francis
                              Title:  President

                           FLEET NATIONAL BANK (f/k/a BankBoston,
                           N.A.), individually and as Agent


                           By: /s/ C. Christopher Smith
                              --------------------------
                              Name:  C. Christopher Smith
                              Title:  Vice President

                           COMERICA BANK


                           By: /s/ Thomas J. Parnell
                              --------------------------
                              Name:  Thomas J. Parnell
                              Title:  Vice President

                           LASALLE BANK NATIONAL ASSOCIATION
                           (f/k/a LaSalle National Bank)


                           By: /s/ David C. Shapiro
                              --------------------------
                              Name:  David C. Shapiro
                              Title:  First Vice President

                           SUNTRUST BANK, SOUTH FLORIDA,
                           NATIONAL ASSOCIATION


                           By: /s/ Byron P. Kurtgis
                              --------------------------
                              Name:  Byron P. Kurtgis
                              Title:  Director