Did you see my suggestion in your first post? Get the sheared screw removed by spark erosion.
This involves an electrode discharging a spark onto the screw. This happens thousands of times a second and each time it removes a minute piece of metal... Last time I had it done it cost about £20 - much cheaper than a new clutch...
Hope this helps!
17-May-2006, 11:43 
Threaded Mode