This Agreement may not be amended, except by an instrument in writing signed on behalf of each of the parties hereto. By an instrument in writing, Purchaser, on the one hand, or Seller, on the other hand, may waive compliance by the other party with any term or provision of this Agreement that such other party was or is obligated to comply with or perform.  Any such waiver shall only be effective in the specific instance and for the specific and limited purpose for which it was given and shall not be deemed a waiver of any other provision of this Agreement or of the same breach or default upon any recurrence thereof.  No failure on the part of any party to exercise, and no delay in exercising, any right hereunder shall operate as a waiver thereof nor shall any single or partial exercise of any right hereunder preclude any other or further exercise thereof or the exercise of any other right.