After having my 91 K100LT painted and after getting it back together I had to bleed the front brakes. Afterwards I noticed it leaking on the glove compartment lid. It appeared to be coming from the plastic resivoir so I pulled it and replaced the "o" ring at the bottom. While I had it apart I noticed there was alot of brake fluid coming out of the piston that is articulated by the hand lever. I looked at the book and it indicates that there are rubber bushings and I'm thinking these are probably the problem. I have also heard that you can't rebuild the master cylinder. Can I just replace the piston or do I need to replace the entire assembly? I looked on Max BMW and it does not look like you can buy the entire assembly.