Jim,
Please ask what clutch disc you have right now because I really don't want to put in another Sachs.
Here is a picture from Joe Paluch as it happened to him before too. I try to be gentle on my downshifts and do heel toe. Clutch was installed on 6/23/05 with 149,725 miles and the car currently has 165K miles so I guess 4 years and 15K miles later of street, driving events and now racing is not too bad.
I have never heard or seen anything like this happen with other aftermarket clutches so that is why I am trying to find something better that is still legal for 944 Spec racing.