AF Cassette clutch issues

[Servetta200]

Went to the Teignmouth rally this weekend and only just made it there.
I had to come back with the RAC.
My clutch was slipping badly and would not hold with the lever in, it gradually got worse.
Tried adjusting the cable but couldn't improve it .
I've stripped it today and the first thing I found was the plunger heavily worn, but I guess they round off with use.
The oil was very metallic.
The circlip on the back of the plunger had come off and was resting inside.
I took a look at the plates and they don't look heavily worn, but I did find two the metal plates warped.
Has anyone else had similar issues?
The clutch has only done a 1000 miles