You know what I'm talking about: the thin black rubber diaphragm just under the brake fluid reservoir cover. Mine's all bolloxed up, and needs replacing. My local dealer (who is usually quite a good source for my parts) says its coming up on the computer as "no longer available"... in which case one would have to replace the entire reservoir to get a new one. Grrrrrr. Anybody know of a source for this part? And a part number? Thanks!