No amendment of any provision of this Amendment shall be valid unless, as a condition to the effectiveness of such change, the same shall be in writing and signed by the party against whom the amendment is sought to be enforced.  No waiver by any party of any default, misrepresentation or breach of warranty or covenant hereunder, whether intentional or not, shall be deemed to extend to any prior or subsequent default, misrepresentation or breach of warranty or covenant hereunder or affect in any way any rights arising by virtue of any prior or subsequent such occurrence.