<PAGE>

                                                                    EXHIBIT 10.6

                                 April 15, 2003

Ambac Assurance Corporation
One State Street Plaza
New York, NY 10004

Wells Fargo Bank Minnesota, National Association,
         as indenture trustee under the Indenture described below
Attention: Corporate Trust Services/Asset-Backed Administration
Sixth Street and Marquette Avenue
MAC N9311-161
Minneapolis, MN 55479
Fax: (612) 667-3464

MFI Finance Corp. I
950 Winter Street, Suite 4100B
Waltham, MA 02451

Leasecomm Corporation
950 Winter Street, Suite 4200
Waltham, MA 02451

Re:      Direction and Permanent Waiver of Trigger Events and Servicer Events of
         Default

Ladies and Gentlemen:

         Reference is made to the (i) Amended and Restated Indenture, dated as
of September 1, 2001, among MicroFinancial Incorporated, MFI Finance Corp. I,
and Wells Fargo Bank Minnesota, National Association ("Wells Fargo"), as amended
and supplemented from time to time (the "Indenture"), pursuant to which Wells
Fargo is appointed to serve as indenture trustee (in such capacity, the
"Indenture Trustee") on behalf of the noteholders and Ambac Assurance
Corporation ("Ambac"), (ii) Servicing Agreement, dated as of March 1, 2000, as
amended from time to time (the "Servicing Agreement"), among MicroFinancial
Incorporated, MFI Finance Corp. I, Wells Fargo, and the Indenture Trustee,
pursuant to which, among other things, Wells Fargo is appointed to serve as
back-up servicer (the "Back-up Servicer"), (iii) Insurance and Indemnity
Agreement, dated December 18, 2000 (the "Series 2000-2 Insurance Agreement"),
among Ambac, MFI Finance Corp. I, Leasecomm Corporation, MicroFinancial
Incorporated, the Indenture Trustee, and the Back-up Servicer, (iv) Insurance
and Indemnity Agreement, dated September 21, 2001 (the "Series 2001-3 Insurance
Agreement" and, together with the Series 2000-2 Insurance Agreement, the
"Insurance Agreements"), among Ambac, MFI Finance Corp. I, Leasecomm
Corporation, MicroFinancial Incorporated, the Indenture Trustee, and the Back-up
Servicer, (v) Amended and Restated Direction and Waiver of Trigger Event and
Servicer Event of Default, dated January 14, 2003 (the "January 14 Waiver"),
among Ambac Assurance Corporation, MicroFinancial Incorporated, and MFI Finance
Corp. I, and acknowledged and agreed to by the Indenture Trustee. Capitalized
terms not otherwise defined herein have the meanings ascribed thereto in the
Indenture.

<PAGE>

         Please execute this Direction and Permanent Waiver in the space
provided below for your signature and return it to the undersigned to evidence
your agreement to the following:

         REPRESENTATIONS AND WARRANTIES REGARDING COVERED EVENTS.

             1.   MicroFinancial Incorporated hereby represents and warrants to
                  Ambac that (a) no Events of Default under the Indenture exist
                  on the date hereof and (b) the only Events of Default (as
                  defined in the Insurance Agreements), Servicer Events of
                  Default and Trigger Events existing on the date hereof (or
                  that would exist absent the January 14 Waiver or this
                  Permanent Waiver) are those that arise directly or indirectly
                  out of the following (collectively, the "Covered Events"):

                       a.   The occurrence of an event of default under the
                            Credit Agreement arising out of any of the following
                            (and terms in this paragraph a related to financial
                            covenants have the meanings ascribed thereto in the
                            Credit Agreement, as applicable) :

                                 i.   for the fiscal quarter ended September 30,
                                      2002, or any fiscal quarter thereafter,
                                      the Fixed Charge Ratio of MicroFinancial
                                      Incorporated and its subsidiaries being
                                      less than 1.30 to 1.00,

                                 ii.  at any time on or after December 31, 2002,
                                      Consolidated Tangible Net Worth of the
                                      Borrower being less than the sum of (x)
                                      $77,500,000 and (y) 50% of the aggregate
                                      amount of Consolidated Net Income of the
                                      Parent and its Subsidiaries, including the
                                      Borrower, for each of the fiscal quarters
                                      ending after June 30, 2000, but without
                                      deducting therefrom any amount of
                                      Consolidated Net Deficit for any of such
                                      fiscal quarters,

                                 iii. at any time on or after September 30, 2002
                                      and before the effective date of the
                                      Credit Agreement Amendment (described
                                      under "Documentation" below), the Total
                                      Outstandings under the Credit Agreement
                                      exceeding the Borrowing Base, or

                                 iv.  Leasecomm Corporation's failure to repay
                                      the Loans on the Borrowing Base Maturity
                                      Date;

                            and in each case such event of default, if any, not
                            being cured, remedied or waived in writing, in
                            accordance with the terms of the Credit Agreement,
                            within 30 days of the date of initial occurrence of
                            such event of default (which could otherwise
                            constitute a Servicer Event of Default under Section
                            6.01(viii) of the Servicing Agreement, leading to a
                            Trigger Event under the Indenture unless waived by
                            the Controlling Party);

                       b.   For the fiscal quarter ended September 30, 2002 or
                            any fiscal quarter thereafter, the fixed charge
                            ratio of the Reported Companies being less than 1.25
                            to 1.0 (which could otherwise constitute a Servicer
                            Event of Default under Section 6.01(xi) of the
                            Servicing Agreement, leading to a Trigger Event
                            under the Indenture if not waived by the Controlling
                            Party);

                       c.   At any time on or after December 31, 2002, the Net
                            Worth Requirement not being met and such failure to
                            meet the Net Worth Requirement remaining uncured for
                            a period of thirty days after delivery of the
                            financial statements reflecting such failure or
                            after the date on which such financial statements
                            were

                                       2

<PAGE>

                           required to have been delivered (which failure, if it
                           remained uncured, could otherwise constitute a
                           Trigger Event under the Indenture unless waived by
                           the Controlling Party).

             2.   MFI Finance Corp. I hereby represents and warrants to Ambac
                  that (a) no Events of Default under the Indenture exist on the
                  date hereof, (b) to the best of MFI Finance Corp. I's
                  knowledge, the only Events of Default (as defined in the
                  Insurance Agreements), Servicer Defaults, and Trigger Events
                  existing on the date hereof (or that would exist absent the
                  January 14 Waiver or this Direction and Permanent Waiver) are
                  those that arise directly or indirectly out of the Covered
                  Events.

             3.   Leasecomm Corporation hereby represents and warrants to Ambac
                  that, to the best of Leasecomm Corporation's knowledge, the
                  only Events of Default (as defined in the Insurance
                  Agreements), Servicer Defaults, and Trigger Events existing on
                  the date hereof (or that would exist absent the January 14
                  Waiver or this Direction and Permanent Waiver) are those that
                  arise directly or indirectly out of the Covered Events.

         PERMANENT WAIVER; DIRECTION TO INDENTURE TRUSTEE

                  In consideration of (a) the representations and warranties
         described above, and (b) receipt of the documentation described under
         "Documentation" below (receipt of which shall be conclusively evidenced
         by Ambac's execution and delivery of a counterpart of this Direction
         and Permanent Waiver), pursuant to Section 6.15 of the Indenture and
         Section 6.04 of the Servicing Agreement, Ambac, as the Controlling
         Party, hereby waives, and directs Wells Fargo Bank Minnesota, National
         Association, as Indenture Trustee, to waive, permanently:

                       a.   each existing Event of Default (as defined in the
                            Insurance Agreements), Servicer Default, and Trigger
                            Event that arises directly or indirectly out of any
                            Covered Event, effective retroactively to the date
                            on which such Event of Default, Servicer Default or
                            Trigger Event occurred; and

                       b.   any present or future Events of Default (as defined
                            in the Insurance Agreements), Servicer Defaults, or
                            Trigger Events that would exist pursuant to the
                            provisions that are being removed from the Servicing
                            Agreement and the Indenture pursuant to the
                            Amendments (the "Removed Provisions").

         DOCUMENTATION

         The "Documentation" referred to above consists of the following:

             1.   Fully executed counterpart of the Third Amendment to Servicing
                  Agreement, to be dated on or about the date hereof, among the
                  parties to the Servicing Agreement, in substantially the form
                  of Exhibit A hereto (as executed and delivered by the parties
                  thereto, the "Servicing Agreement Amendment");

             2.   Fully executed counterpart of the First Amendment to Amended
                  and Restated Indenture, to be dated on or about the date
                  hereof, among the parties to the Indenture, in substantially
                  the form of Exhibit B hereto (as executed and delivered by the
                  parties thereto, the "Indenture Amendment" and, together with
                  the Servicing Agreement Amendment, the "Amendments");

                                       3

<PAGE>

             3.   Fully executed counterpart of Second Amendment to Fourth
                  Amended and Restated Revolving Credit Agreement, dated on or
                  about March 31, 2003 (the "Credit Agreement Amendment"), among
                  Leasecomm Corporation, Fleet National Bank and the other
                  financial institutions from time to time party to the Fourth
                  Amended and Restated Revolving Credit Agreement, and Fleet
                  National Bank, as agent;

             4.   Fully executed counterpart of this Direction and Permanent
                  Waiver, acknowledged and agreed to by the Indenture Trustee;

             5.   Waiver fee of $50,000; and

             6.   Permanent waiver by N M Rothschild & Sons Limited of any
                  "servicer events of default" and any consequent "trigger
                  events" under the indenture and servicing agreement related to
                  MFI Finance II, LLC in any way related to the Covered Events
                  or the Removed Provisions.

WAIVER LIMITED TO DESCRIBED EVENTS.

         We expressly acknowledge and agree that the foregoing waivers do not
apply to any Trigger Event, Servicer Event of Default, Event of Default, Event
of Default (as defined in the Insurance Agreements) or other default or similar
event not described under "Permanent Waiver" above (whether occurring before or
after the date hereof).

AGREEMENT TO PAY REASONABLE FEES AND EXPENSES.

         MicroFinancial Incorporated agrees to pay to Jones Day, promptly upon
receipt of an invoice therefor, the reasonable fees and expenses of such firm in
connection with its representation of Ambac in connection with the negotiation
of this Direction and Permanent Waiver and related matters.

                                       4

<PAGE>

COUNTERPARTS

         This Direction and Permanent Waiver may be executed and delivered in
any number of counterparts, each of which when so executed and delivered shall
be deemed to be an original, but all such counterparts shall together constitute
but one and the same instrument. Delivery of an executed counterpart of a
signature page to this Direction and Permanent Waiver by telecopier shall be as
effective as delivery of a manually executed counterpart of this Direction and
Permanent Waiver.

                                      Very truly yours,

                                      MICROFINANCIAL, INCORPORATED

                                      By:    /S/ Richard F. Latour
                                             --------------------------
                                      Name:  Richard F. Latour
                                      Title: President and CFO

CONSENTED & AGREED TO BY:

MFI FINANCE CORP. I

By:    /S/ Peter R. von Bleyleben
       ---------------------------------
Name:  Peter R. von Bleyleben
Title: President

LEASECOMM CORPORATION

By:    /S/ Peter R. von Bleyleben
       ---------------------------------
Name:  Peter R. von Bleyleben
Title: President

AMBAC ASSURANCE CORPORATION

By:    /S/ Harris C. Mehos
       ---------------------------
Name:  Harris C. Mehos
Title: First Vice President

<PAGE>

INDENTURE TRUSTEE ACKNOWLEDGMENT

The Indenture Trustee hereby acknowledges and agrees to the foregoing, and
pursuant to Section 6.15 of the Indenture and Section 6.04 of the Servicing
Agreement hereby permanently waives the within mentioned Servicer Events of
Default and Trigger Events.

WELLS FARGO BANK MINNESOTA, NATIONAL ASSOCIATION, as Indenture Trustee


By: /s/ Cheryl Zimmerman
    -------------------------------
    Name: Cheryl Zimmerman
    Title: Corporate Trust Officer
    Date: 4/14/03