<PAGE>   1
                                                                   EXHIBIT 10.31




                                                                  EXECUTION COPY

                            THE CERPLEX GROUP, INC.

                      EXTENSION AND FORBEARANCE AGREEMENT


                 This EXTENSION AND FORBEARANCE AGREEMENT (this "Agreement") is
dated as of March 31, 1997 and entered into by and among THE CERPLEX GROUP,
INC., a Delaware corporation ("COMPANY"), the FINANCIAL INSTITUTIONS LISTED ON
THE SIGNATURE PAGES HEREOF ("LENDERS") and WELLS FARGO BANK NATIONAL
ASSOCIATION, as administrative agent for Lenders ("ADMINISTRATIVE AGENT"), and,
for purposes of Section 4 hereof, CERTECH Technology, Inc., Cerplex Mass.,
Inc., Cerplex Limited, Apex Computer Company, Cerplex Subsidiary, Inc.,
Peripheral Computer Support, Inc., Modcomp/Cerplex L.P., Modcomp Joint Venture,
Inc., Modular Computer Services, Inc., Modular Computer Systems GmbH and
Modcomp France S.A.  (collectively, "GUARANTORS"), and is made with reference
to that certain Credit Agreement dated as of October 12, 1994, as amended by
that certain First Amendment to Credit Agreement and Limited Waiver dated as of
April 15, 1996 and that certain Second Amendment to Credit Agreement and
Limited Waiver dated as of November 30, 1996 (the "CREDIT AGREEMENT"), by and
among Company, Lenders Administrative Agent and Guarantors.  Capitalized terms
used herein without definition shall have the same meanings herein as set forth
in the Credit Agreement.

                                    RECITALS

                 WHEREAS, the Commitment Termination Date with respect to the
Loans outstanding under the Credit Agreement is March 31, 1997; and

                 WHEREAS, Company and Lenders have entered into negotiations to
restructure certain of the Loans outstanding under the Credit Agreement; and

                 WHEREAS, Company and Lenders desire to enter into this
Agreement in order to provide time to determine whether or not the parties are
able to reach an agreement with respect to the terms of such a restructure;

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

SECTION 1.  EXTENSION

                 Lenders hereby agree to extend the Commitment Termination Date
under the Credit Agreement to and including the earlier of (i) the date on
which any agreement by the parties to the Note Purchase Agreement waiving all
defaults under the Note Purchase Agreement expires or is terminated and (ii)
April 9, 1997 (the period from the date hereof to




                                       1
<PAGE>   2
the earlier of the dates referred to in clause (i) and (ii) being referred to
herein as the "EXTENSION PERIOD").  During the Extension Period, the Credit
Agreement shall remain in full force and effect in accordance with its terms
except that no Loans shall be extended to Company.

                 The agreement of Lenders set forth herein is not, and should
not be construed to be, a commitment to further extend the Commitment
Termination Date or to restructure any of the obligations under the Credit
Agreement.  Company hereby acknowledges that any restructuring is subject to
the negotiation, execution and delivery of definitive agreements, in each case
satisfactory to all Lenders, Administrative Agent and their respective counsel.
Company hereby further acknowledges that no Lender may enter into any agreement
relating to a restructuring of Company's obligations under the Credit Agreement
and the other Loan Documents unless it obtains all necessary approvals required
under its internal credit approval policies and procedures.  No statements made
by any representative of any Lender of Administrative Agent shall be construed
as a commitment of, and no such statement shall bind, any Lender or
Administrative Agent.  Only a fully approved, signed and delivered agreement
shall constitute or be deemed to constitute a binding agreement.  Moreover, no
agreement relating to any restructuring issue shall create a binding obligation
until an agreement is reached on all such issues and reduced to a fully
approved, executed and delivered written contract.

                 Company has informed Administrative Agent that as of March 31,
1997 Company will be in default under subsection 7.6 of the Credit Agreement
(the "EXISTING DEFAULTS").  Subject to the terms and conditions set forth
herein and in reliance on the representations and warranties of Company herein
contained, Lenders hereby agree to forbear from the exercise of remedies that
are or may be available under the Credit Agreement and the other Loan Documents
by reason of the occurrence and continuation of such Defaults during the
Extension Period.

                 The agreement of Lenders set forth herein shall not in any
manner limit or impair any rights or remedies that Lenders may have (i) at the
expiration of the Extension Period or (ii) with respect to any Defaults or
Events of Default (other than the Existing Defaults) during the Extension
Period.

SECTION 2.       CONDITIONS TO EFFECTIVENESS

                 This Agreement shall become effective as of the date hereof
only upon the satisfaction of all of the following conditions precedent:

         A.      Company shall deliver to Lenders (or to Administrative Agent
for Lenders with sufficient originally executed copies, where appropriate, for
each Lender and its counsel) the following:

                 (i)      Resolutions of its Board of Directors approving and
         authorizing the execution, delivery, and performance of this
         Agreement, certified as of the date





                                       2
<PAGE>   3
         hereof by its corporate secretary or an assistant secretary as being
         in full force and effect without modification or amendment;

                 (ii)     Signature and incumbency certificates of its officers
         executing this Agreement dated as of the date hereof; and

                 (iii)    Duly executed Allonges extending the maturity date of
         the Notes.

         B.      Company and all Lenders shall have delivered (including by
facsimile transmission) originally executed copies of this Agreement to
Administrative Agent.

         C.      Lenders and their respective counsel shall have received
originally executed copies of one or more favorable written opinions of
Brobeck, Phleger & Harrison, counsel for Company, dated March 31, 1997, in form
and substance reasonably satisfactory to Administrative Agent and its counsel
as to such matters as Administrative Agent acting on behalf of Lenders may
reasonably request.

         D.      Administrative Agent, on behalf of Lenders, shall have
received duly executed copies of an agreement, in form and substance
satisfactory to Lenders, waiving all defaults under the Note Purchase Agreement
until April 9, 1997.

SECTION 3.       COMPANY'S REPRESENTATIONS AND WARRANTIES

                 In order to induce Lenders to enter into this Agreement,
Company represents and warrants to each Lender that the following statements
are true, correct and complete:

         A.      CORPORATE POWER AND AUTHORITY.  Company has all requisite
corporate power and authority to enter into this Agreement.

         B.      AUTHORIZATION OF AGREEMENTS.  The execution and delivery of
this Agreement have been duly authorized by all necessary corporate action on
the part of Company.

         C.      NO CONFLICT.  The execution and delivery by Company of this
Agreement do not and will not (i) violate any provision of any law or any
governmental rule or regulation applicable to Company or any of its
Subsidiaries, the Certificate or Articles of Incorporation or Bylaws of Company
or any of its Subsidiaries or any order, judgment or decree of any court or
other agency of government binding on Company or any of its Subsidiaries, (ii)
conflict with, result in a breach of or constitute (with due notice or lapse of
time or both) a default under any Contractual Obligation of Company or any of
its Subsidiaries, (iii) result in or require the creation or imposition of any
Lien upon any of the properties or assets of Company or any of its Subsidiaries
(other than any Liens created under any of the Loan Documents in favor of
Administrative Agent on behalf of Lenders), or (iv) require any approval of
stockholders or any approval or consent of any Person under any Contractual
Obligation of Company or any of its Subsidiaries.





                                       3
<PAGE>   4
         D.      GOVERNMENTAL CONSENTS.  The execution and delivery by Company
of this Agreement do not and will not require any registration with, consent or
approval of, or notice to, or other action to, with or by, any federal, state
or other governmental authority or regulatory body.

         E.      BINDING OBLIGATION.  This Agreement has been duly executed and
delivered by Company and is the legally valid and binding obligations of
Company, enforceable against Company in accordance with their respective terms,
except as may be limited by bankruptcy, insolvency, reorganization, moratorium
or similar laws relating to or limiting creditors' rights generally or by
equitable principles relating to enforceability.

SECTION 4.       ACKNOWLEDGEMENT AND CONSENT

                 Company is a party to the Company Collateral Documents, in
each case as amended through the date hereof, pursuant to which Company has
created Liens in favor of Administrative Agent on certain Collateral to secure
the Obligations.  Guarantors are a party to the Guaranty and the Subsidiary
Collateral Documents, in each case as amended through the date hereof, pursuant
to which each Guarantor has (i) guarantied the Obligations and (ii) created
Liens in favor of Administrative Agent on certain Collateral to secure the
obligations of such Grantor under the Guaranty.  Company and Guarantors are
collectively referred to herein as the "CREDIT SUPPORT PARTIES", and the
Guaranty, the Company Collateral Documents and the Subsidiary Collateral
Documents are collective referred to herein as the "CREDIT SUPPORT DOCUMENTS".

                 Each Credit Support Party hereby confirms that each Credit
Support Document to which it is a party or otherwise bound and all Collateral
encumbered thereby will continue to guaranty or secure, as the case may be, to
the fullest extent possible the payment and performance of all "Obligations,"
"Guarantied Obligations" and "Secured Obligations," as the case may be (in each
case as such terms are defined in the applicable Credit Support Document),
including, without limitation, the payment and performance of all such
"Obligations," "Guarantied Obligations" or "Secured Obligations," as the case
may be, in respect of the Obligations of Company now or hereafter existing
under or in respect of the Credit Agreement and the Notes defined therein.

                 Each Credit Support Party acknowledges and agrees that any of
the Credit Support Documents to which it is a party or otherwise bound shall
continue in full force and effect and that all of its obligations thereunder
shall be valid and enforceable.

SECTION 5.  MISCELLANEOUS

         A.      HEADINGS.  Section and subsection headings in this Agreement
are included herein for convenience of reference only and shall not constitute
a part of this Agreement for any other purpose or be given any substantive
effect.





                                       4
<PAGE>   5
         B.      APPLICABLE LAW.  THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS
OF THE PARTIES HEREUNDER SHALL BE GOVERNED BY, AND SHALL BE CONSTRUED AND
ENFORCED IN ACCORDANCE WITH, THE INTERNAL LAWS OF THE STATE OF CALIFORNIA,
WITHOUT REGARD TO CONFLICTS OF LAWS PRINCIPLES.

         C.      COUNTERPARTS.  This Agreement may be executed in any number of
counterparts and by different parties hereto in separate counterparts, each of
which when so executed and delivered shall be deemed an original, but all such
counterparts together shall constitute but one and the same instrument;
signature pages may be detached from multiple separate counterparts and
attached to a single counterpart so that all signature pages are physically
attached to the same document.





                                       5
<PAGE>   6
                 IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be duly executed and delivered by their respective officers
thereunto duly authorized as of the date first written above.

                                   THE CERPLEX GROUP, INC.


                                   By: _________________________________________
                                   Title: ______________________________________


                                   CERTECH TECHNOLOGY, INC. (for purposes 
                                   of Section 4 only) as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________


                                   CERPLEX MASS., INC., (for purposes of 
                                   Section 4 only) as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________


                                   CERPLEX LIMITED (for purposes of 
                                   Section 4 only) as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________


                                   APEX COMPUTER COMPANY (for purposes of 
                                   Section 4 only) as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________





                                       6
<PAGE>   7
                                   CERPLEX SUBSIDIARY, INC. (for purposes of 
                                   Section 4 only) as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________


                                   PERIPHERAL COMPUTER SUPPORT, INC. 
                                   (for purposes of Section 4 only) 
                                   as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________


                                   MODCOMP/CERPLEX L.P. (for purposes of 
                                   Section 4 only) as a Credit Support Party

                                   By:  Cerplex Subsidiary, Inc., 
                                        as general partner


                                   By: _________________________________________
                                   Title: ______________________________________


                                   MODCOMP JOINT VENTURE, INC. (for purposes 
                                   of Section 4 only) as a Credit Support 
                                   Party


                                   By: _________________________________________
                                   Title: ______________________________________


                                   MODULAR COMPUTER SERVICES, INC.(for purposes 
                                   of Section 4 only) as a Credit Support Party


                                   By: _________________________________________
                                   Title: ______________________________________





                                       7
<PAGE>   8

                                  MODULAR COMPUTER SYSTEM GMBH (for purposes of 
                                  Section 4 only) as a Credit Support Party


                                  By: _________________________________________
                                  Title: ______________________________________


                                  MODCOMP FRANCE S.A. (for purposes of 
                                  Section 4 only) as a Credit Support Party


                                  By: _________________________________________
                                  Title: ______________________________________


                                  WELLS FARGO BANK, NATIONAL ASSOCIATION, 
                                  Individually and as Administrative Agent


                                  By: _________________________________________
                                  Title: ______________________________________


                                  SUMITOMO BANK OF CALIFORNIA, as a Lender


                                  By: _________________________________________
                                  Title: ______________________________________


                                  BHF-BANK AKTIENGESELLSCHAFT, as a Lender


                                  By: _________________________________________
                                  Title: ______________________________________





                                       8
<PAGE>   9
                                   COMMERCIAL BANK CALIFORNIA, as a Lender


                                   By: _________________________________________
                                   Title: ______________________________________





                                       9