Note the groove - designed to act as a release, should clutch fluid escape past the piston. This groove prevents it from being forced past the other seal and into the engine.

Note the distorted dowel. The photo makes it look easy to get at. It isn't - its tucked behind the exhaust pipe, and the whole unti is behind the front wheel. I distorted the peg trying to get it out to make it easier top scrape off the old gasket. I then had to make a tool to make it round again - a piece of metal with a hole drilled the right size and countersunk. Work the tool over the dowel and rotate back and forth. Grinding past helped a lot here as well.

To get it all back on, I had to release the exhaust clamps at the cylinder head. This requires thje lower fairing to be removed, along with the crash bar stays - just to get at the nuts. It provides enough freedom to get a socket in to the clutch release housing.

So how did I get it off ? - well you can spring the exhaust out of the way by using the clutch release housing as a bit of a lever - it doesn't need much force, so its OK. - But of course the housing isn't there when you are putting it back on is it? Doh !