my clutch failed on a recent trip away, (lever pulling back to bar with no effect) sussed that by bleeding masses of air out of it (master cylinder air bleed screw) I could get it working again. it would then get progressively worse as the day went on, till I did it again.
got home OK, and stripped down the master cylinder, it had a lot of grit in it, which had actually been wearing away at it, as the rubber seal had a feathered edge, and scoring down the sides.
I had read that these were not replacable, one of my friends has a bearing shop, they got a replacement the next day. it is now fitted total time around an hour inc cleaning and replaceing my 15T front sprocket. and appears to be working, a test ride at the weekend will tell for sure.
thought i would write it up for other people with same problem, as I find these sites a great reference for this sort of stuff.
master cylinder seal
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