<PAGE>

                                                                 EXHIBIT 10.23.1


   AMENDMENT #1 TO THE THIRD RESTATED AND AMENDED LOAN AND SECURITY AGREEMENT

September 20, 2004

JACO ELECTRONICS, INC. ("Jaco")
145 Oser Avenue
Hauppauge, NY  11778

NEXUS CUSTOM ELECTRONICS, INC. ("Nexus")
Prospect Street
Brandon, VT  05733

INTERFACE ELECTRONICS, INC. ("Interface")
124 Grove Street
Franklin, MA  02028

Gentlemen:

            Reference is made to the Third Restated and Amended Loan and
Security Agreement in effect between GMAC Commercial Finance LLC, as successor
by merger to GMAC Commercial Credit LLC, which was the successor in interest to
BNY Financial Corporation ("GMAC"), as Agent and Lender, and PNC Bank National
Association ("PNC") as Lender and Co-Agent, and Jaco, Nexus and Interface, dated
December 22, 2003, as supplemented and amended from time to time, (the
"Agreement"). Both GMAC and PNC may hereinafter be referred to jointly as the
"Lenders", and individually, as a "Lender" and GMAC may also be herein referred
to as "Agent" when acting in such capacity, as the case may be and PNC may also
herein be referred as "Co-Agent", as the case may be. Initially capitalized
terms not defined herein shall have the meanings ascribed to such terms in the
Agreement. Jaco, Nexus and Interface may hereinafter and in the Agreement, be
referred to jointly and severally as "Debtors", and each individually as a
"Debtor".

            WHEREAS you have informed us that you intend to sell substantially
all of the assets of Nexus to Sagamore Advisors LLC (the "Buyer") for a purchase
price in the amount of $9,250,000 in cash (the "Cash Portion of the Purchase
Price"), a subordinated promissory note in the amount of $2,750,000 (the "Note")
and an additional $1,000,000 in cash based on performance of the purchaser after
the completion of the sale (the "Cash Performance Amount"); and

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            WHEREAS you have requested the Agent and the Lenders consent to the
proposed sale (as required by the terms of the Agreement), subject to the terms
and conditions, outlined in a certain letter of intent (the "Letter of Intent"),
between Jaco and the Buyer, dated July 6, 2004 (the "Sale"); and

            WHEREAS the Agent and the Lenders are willing to give the requested
consent subject to the terms and conditions stated herein below;

            NOW THEREFORE IT IS HEREBY AGREED AS FOLLOWS:

            Effective as of the closing date of the Sale, the Agreement is
            hereby amended as follows:

               1. The definition of "Contract Rate" as stated in Sub-Section 1.2
                  of the Agreement is hereby deleted in its entirety and
                  replaced by the following definition:

                           " "Contract Rate" shall mean, as applicable, with
                           respect to Revolving Advances, an interest rate per
                           annum equal to (i) the Base Rate plus three-quarters
                           of one (.75%) percent or (ii) the Eurodollar Rate
                           plus three (3%) percent, as applicable (provided
                           however, that it shall mean the Eurodollar Rate plus
                           three and one-quarter (3.25%) percent, until
                           September 30, 2005. However, the Contract Rate, for
                           Eurodollar Rate Loans, shall continue to mean the
                           Eurodollar Rate plus three and one-quarter (3.25%)
                           percent, after September 30, 2005, if the Fixed
                           Charge Coverage Ratio on September 30, 2005,
                           calculated on a four (4) quarter rolling basis, for
                           the previous four (4) quarters, shall be less than
                           1.1 to 1.0, until such time as the Fixed Charge
                           Coverage Ratio shall be equal to or greater than 1.1
                           to 1.0 at the end of any fiscal quarter ending after
                           September 30, 2005, calculated on a four (4) quarter
                           rolling basis, for the previous four (4) quarters.)"

               2. Section 6.9(a), of the Agreement, is hereby deleted in its
                  entirety and replaced by the following:

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                        "6.9. Financial Covenants.

                              (a) EBITDA. Maintain EBITDA for the Loan Parties
                              on a Consolidated Basis as of the end of each
                              fiscal quarter set forth below for the respective
                              fiscal periods set forth below ending on the last
                              day of such fiscal quarter in an amount not less
                              than the amount set forth below:

<TABLE>
<CAPTION>
Fiscal Period                                 Minimum EBITDA
-------------                                 --------------
<S>                                           <C>
Fiscal Quarter Ending 12/31/03                $   400,000
Fiscal Quarter Ending  3/31/04                $ 1,000,000
Fiscal Quarter Ending  6/30/04                $ 1,300,000
Fiscal Quarter Ending  9/30/04                $   235,000
Fiscal Quarter Ending 12/31/04                $   400,000
</TABLE>

                              (b) Fixed Charge Coverage Ratio. Maintain as of
                              the end of each quarter, on a four quarter rolling
                              basis for the previous four quarters, a Fixed
                              Charge Coverage Ratio for the Loan Parties on a
                              Consolidated Basis as of the end of each fiscal
                              quarter set forth below for the respective periods
                              set forth below of not less than the ratios set
                              forth below:

<TABLE>
<CAPTION>
Fiscal Period Ending                             Fixed Charge Coverage Ratio
--------------------                             ---------------------------
<S>                                              <C>
   3/31/05                                          1.0 to 1.0
   6/30/05                                          1.0 to 1.0
   9/30/05 and any fiscal period thereafter         1.1 to 1.0"
</TABLE>

            3.    Sub-Section 6.10, of the Agreement, shall be deleted in its
                  entirety and replaced by the following:

                        "6.10. Minimum Net Worth.

                              Maintain at all times a minimum Net Worth of at
                              least $44,500,000 to be increased for each fiscal
                              year by sixty-five (65%) percent of fiscal year
                              end net income (excluding net income from the Sale
                              of Nexus) and increased by eighty (80%) percent of
                              the profit from the sale of the assets of Nexus
                              (during the fiscal year of such sale) and reduced
                              by eighty (80%) percent of the amount of any
                              write-off amount (if any) of the note executed by
                              the buyer of such assets for the benefit of Jaco
                              (during the fiscal year of any such write-off)."

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            4.    The following Sub-Section 6.12 shall be added to Section VI of
                  the Agreement.

                        "6.12. Permanent Undrawn Availability .

                              Maintain at all times (for all Loan Parties) an
                              aggregate Undrawn Availability of $1, 500,000,
                              provided however, that such Undrawn Availability
                              may be reduced to $500, 000 at all times on the
                              later to occur of (i) 3-31-05 or (ii) the last day
                              of the second consecutive fiscal quarter during
                              which the Fixed Charge Coverage Ratio equals 1.1
                              to 1.0, calculated on a rolling four quarter
                              basis, excluding any profits derived from the
                              Sale."

            5.    Sub-Section 7.6, of the Agreement, is hereby deleted in its
                  entirety and replaced by the following:

                        "7.6. Capital Expenditures.

                              Contract for, purchase or make any net Capital
                              Expenditures, as of each fiscal year, in an amount
                              not exceeding the amount stated opposite such
                              fiscal year in the table below.

<TABLE>
<CAPTION>
Fiscal Year Ending                             Amount
------------------                             ------
<S>                                           <C>
  6/30/04                                     $750,000
  6/30/05 and each fiscal year thereafter     $500,000"
</TABLE>

            6.    Notwithstanding anything contrary in the Agreement, as of the
                  closing date of the Sale, the Effective Additional
                  Availability Amount shall be reduced to zero (0).

            7.    The Agent and the Lenders hereby consent to the Sale of all of
                  the assets of Nexus, subject to the terms and conditions of
                  the Letter of Intent, and the sales agreement executed
                  pursuant thereto dated September __, 2004, provided Lender
                  receives the Cash Portion of the Purchase Price. The Agent, on
                  behalf of the Lenders, shall release, as of the date of the
                  closing of the Sale, upon receipt of the Cash Portion of the
                  Purchase Price at the account specified below, any and all
                  liens it may have on the assets of Nexus in which the Agent
                  and/or the Lenders presently have a lien on or a security
                  interest in and agree, at Borrowers' expense, to execute all
                  necessary releases and financing statements, as may reasonably
                  be requested by Borrowers. Borrowers hereby agree to also
                  arrange to have the proceeds of the Note and the Cash
                  Performance Amount to be wired transferred to the account
                  specified below. The Cash Portion of the Purchase Price, the
                  proceeds of the Note and the Cash Performance

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                  Amount (if any) shall be applied, by the Agent, to reduce the
                  amount of the Obligations in accordance, with the terms of the
                  Agreement. The Cash Portion of the Purchase Price, the
                  proceeds of the Note and the Cash Performance Amount (if any)
                  shall be wire transferred to the Agent's account as follows:

                        "BANK ONE NA
                         ABA # 072000326
                         Account # 361324984
                         Attention Operations Department
                         For the account of GMAC Commercial Finance LLC
                         Reference Jaco Electronics, Inc."

            8.    As additional Collateral and inconsideration of the Sale, Jaco
                  shall pledge and assign, to the Agent, for the pro rata
                  benefit of the Lenders, the Note.

            9.    In consideration of the foregoing consent, Loan Parties hereby
                  agree to pay, the Agent, a fee of $25,000 for the pro rata
                  benefit of the Lenders on September 20, 2004. The Loan Parties
                  hereby authorize the Lender to automatically charge to
                  Borrowers' account with the amount of such fee, as of such
                  date.

            10.   By their signatures below, Jaco, Nexus and Interface hereby
                  ratify the Agreement (as hereby amended) and agree to be
                  jointly and severally liable for all Obligations under the
                  Agreement and agree that all of the outstanding amounts of the
                  Loans under the Agreement, as of the date hereof, shall be
                  valid and binding Obligations of each of them, and shall be
                  deemed Obligations outstanding under the Agreement, and hereby
                  agree and promise to repay to the Agent, for the benefit of
                  the Lenders, such Obligations (including but not limited to
                  all applicable interest) in accordance with the terms of the
                  Agreement, but in no event, later than the Termination Date.

            11.   By their signatures below, Jaco, Nexus and Interface hereby
                  ratify and affirm to the Agent that as of the date hereof,
                  they are in full compliance with all covenants under the
                  Agreement (except as waived above) and certify that all
                  representations and warranties of the Agreement are true and
                  accurate as of the date hereof, with the same effect as if
                  they had been made as of the date hereof.

      Except as herein specifically amended, the Agreement shall remain in full
force and effect in accordance with its original terms, except as previously
amended.

      If the foregoing accurately reflects our understanding, kindly sign the
enclosed

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copy of this letter and return it to our office as soon as practicable.

                                                 Very truly yours,
                                                 GMAC COMMERCIAL FINANCE LLC
                                                 (as Agent and Lender)

                                                 By: /s/ Daniel Murray
                                                     ---------------------------
                                                     Title: 1st. Vice President

AGREED AND ACCEPTED:
JACO ELECTRONICS, INC.                           PNC BANK NATIONAL ASSOCIATION
                                                 (as Lender)

By:  /s/ Jeffrey D. Gash                         By:  /s/ Wing Louie
    ---------------------------------                ---------------------------
    Title: Vice President - Secretary                Title: Vice President

NEXUS CUSTOM ELECTRONICS, INC.                   INTERFACE ELECTRONICS CORP.

By:  /s/ Jeffrey D. Gash                         By:  /s/ Jeffrey D. Gash
    ---------------------------------                ---------------------------
    Title: Vice President                            Title: Vice President

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