I emailed Spec last night and they got back to me right away in the morning. This is what they said:
Really depends on what stage clutch it is. Stage 2 (Kevlar) is pretty much done if you glazed it. If the clutch has wear, you might not want to sand it down much, but if it still looks okay, and is sufficient thickness, then you might be fine just taking off the surface with a scotchbrite pad or something similar.
Do you have a part number or particular stage and application? Worst case, we could put new clutch facing on there if you send it in… not terribly expensive.
That's pretty cool if them, I think. Anyway, I'm posting this hear in case anyone else searches for this.
Thanks,
Darian