<PAGE>

                                                                    Exhibit 10.1

                           VESTAR/GRAY INVESTORS LLC

          AMENDMENT, dated as of June 4, 2001 (the "Amendment"), to the Amended
                                                    ---------
and Restated Limited Liability Company Agreement (the "LLC Agreement") of
                                                       -------------
Vestar/Gray Investors LLC, a Delaware limited liability company (the "LLC"),
                                                                      ---
dated as of July 7, 1999, by and among Vestar/SJK Investors LLC, a Delaware
limited liability company (the "Vestar Member"), the parties listed on Schedule
                                -------------
1 to the LLC Agreement (each a "Gray Member" and, collectively, the "Gray
                                -----------                          ----
Members") and such other Persons as shall hereinafter become Members of the LLC
-------
as provided in the LLC Agreement.

                              W I T N E S S E T H
                              -------------------

          WHEREAS, the LLC, the Vestar Member and the Gray Members are parties
to the LLC Agreement; and

          WHEREAS, the parties desire to amend the LLC Agreement as set forth
herein.

          NOW, THEREFORE, in consideration of the mutual covenants and
agreements herein made and intending to be legally bound hereby, the parties
hereto hereby agree as follows:

          1.   Defined Terms. Unless otherwise defined herein, capitalized terms
               -------------
used herein which are defined in the LLC Agreement are used herein as therein
defined.

          2.   Amendment to the LLC Agreement.  The LLC Agreement is hereby
               ------------------------------
amended as follows:

               (a)  Amendment of Section 1.1.  Section 1.1 of the LLC Agreement
                    ------------------------
     is hereby amended by adding, in appropriate alphabetical order, the
     following new definition:

               "Chief Executive Officer" shall mean, in the case of the Company,
               -------------------------
          the Chief Executive Officer of the Company, and, in the case of the
          Parent, the Chief Executive Officer of the Parent.

          (b)  Amendment of Section 4.9(b)(A).  Section 4.9(b)(A) of the LLC
               -----------------------------
Agreement is hereby amended by deleting such Section in its entirety and
replacing it with the following:

               (b)  Election of Directors.

                    (A)  The Managing Member hereby agrees that so long as this
       Agreement shall remain in effect, it will vote all of the Shares so as to
       elect and, during such period, to continue in office a Board of Directors
       of the Parent and the Company, each consisting solely of the following:

                    (i)  4 designees of the Vestar Member (so long as the Vestar
                         Member and its Affiliates are allocated an aggregate
<PAGE>

                                                                               2



                         number of Allocated Shares not less than one-half (1/2)
                         of the number of Allocated Shares allocated to the
                         Vestar Member on the date of execution and delivery of
                         this Agreement) or, if the foregoing condition is not
                         satisfied, 3 designees of the Vestar Member (so long as
                         the Vestar Member and its Affiliates are allocated an
                         aggregate number of Allocated Shares not less than one-
                         third (1/3) of the total number of Allocated Shares
                         allocated to the Vestar Member on the date of its
                         execution and delivery of this Agreement) or, if the
                         foregoing condition is not satisfied, 1 designee of the
                         Vestar Member (so long as the Vestar Member and its
                         Affiliates are allocated an aggregate number of
                         Allocated Shares not less than one-tenth (1/10) of the
                         total number of Allocated Shares allocated to the
                         Vestar Member immediately following the Effective Time
                         of the Acquisition Merger), provided, however, that so
                                                     --------  -------
                         long as the Gray Members have the right to appoint at
                         least 1 designee and the Vestar Member (and its
                         Affiliates) has more Allocated Shares allocated to it
                         than the aggregate number of Allocated Shares allocated
                         to the Gray Members (and their Permitted Transferees),
                         the Vestar Member shall have the right to appoint at
                         least as many designees as the Gray Members;

                  (ii)   2 designees of the Gray Members (so long as the Gray
                         Members and their respective Affiliates are allocated
                         an aggregate number of Allocated Shares not less than
                         one-half (1/2) of the number of Allocated Shares
                         allocated to the Gray Members on the date of their
                         execution and delivery of this Agreement) or, if the
                         foregoing condition is not satisfied, 1 designee of the
                         Gray Members (so long as the Gray Members and their
                         respective Affiliates are allocated an aggregate number
                         of Allocated Shares not less than one-fifth (1/5) of
                         the number of Allocated Shares allocated to the Gray
                         Members immediately following the Effective Time of the
                         Acquisition Merger); and

                  (iii)  the Chief Executive Officer (provided that such Chief
                         Executive Officer is not (A) an employee or an
                         Affiliate of Vestar or (B) a Gray Member or a member of
                         the Family Group of the Gray Members, in which case the
                         Chief Executive Officer shall be counted as a designee
                         of either Vestar or the Gray Representative, as the
                         case may be, for purposes of this Section 4.9(b)(A)).


<PAGE>

                                                                               3

          3.   Continuing Effect of LLC Agreement.  This Amendment shall not
               ----------------------------------
constitute an amendment or waiver of or consent to any provision of the LLC
Agreement not expressly referred to herein.  Except as expressly consented to
hereby, the provisions of the LLC Agreement are and shall remain in full force
and effect.

          4.   Counterparts.  This Amendment may be executed in any number of
               ------------
counterparts, all of which together shall constitute a single instrument.

          5.   Governing Law.  This Amendment shall be governed by and construed
               -------------
in accordance with the laws of the State of Delaware applicable to contracts
executed and to be performed in such State.
<PAGE>

          IN WITNESS WHEREOF, the parties have executed this Amendment as of the
day and year first above written.


                             VESTAR/SJK INVESTORS LLC

                             By:  Vestar Capital Partners III, L.P.,
                                  its Managing Member

                                    By:  Vestar Associates III, L.P.,
                                          its General Partner

                                    By:  Vestar Associates Corporation III,
                                          its General Partner



                             By:          /s/ James P. Kelley
                                ------------------------------------------------
                                 Name:        James P. Kelley
<PAGE>

                               /s/  Bob Gray
                               -------------------------------------------------
                               BOB GRAY


                                /s/  Marie Gray
                               -------------------------------------------------
                               MARIE GRAY


                                /s/  Kelly A. Gray
                               -------------------------------------------------
                               KELLY A. GRAY


                               GRAY FAMILY TRUST


                               By:    /s/ Bob Gray
                                   ---------------------------------------------
                                   Name:    Bob Gray


                               By:    /s/ Marie Gray
                                   ---------------------------------------------
                                   Name:    Marie Gray


                               KELLY ANN GRAY TRUST


                               By:    /s/ Bob Gray
                                   ---------------------------------------------
                                   Name:    Bob Gray


                               By:    /s/ Marie Gray
                                   ---------------------------------------------
                                   Name:    Marie Gray