Very easy to make one from gasket paper or a corn flake box with a smear of silicon. The originals are quite thin.
BTW, we call it a "Bowler Hat"

Ron

email (option): ronpier@talk21.com

I think you are looking in the wrong places, I expect that gasket if it's 15-4316 would be about £2.00ukp though £4.20ukp for uninsured postage.

email (option): pes.sales@btconnect.com

I prolly have several Charlie.

email (option): britool51@hotmail.com