Thanks for the lead, I will contact them this week and see if I cannot get somewhere with this. I didn't know what they were made of... Today I Learned...Forget sanding or blasting clutch plates or fibres. It's a stop gap or temporary measure. It works for a while, then it doesn't. It's a waste of time IMHO.
Get some new springs, fibre plates and steel plates. Barnett should be able to supply them, they make clutches for about everything.
Danger, is my business."