Are you talking about the rubber mat or the mylar sheets with the circuitry?
Unicomp refers to the rubber as the "blanket" and it does not serve any electrical purpose beyond padding and insulation. If that is what is stuck, I would soak it in water. Chances are, it was a sugar drink spill that got in there and hardened.
If you mean the clear layers with traces, you will have to be much more careful.
And, I agree, you should be able to do a bolt mod anyway. I have never encountered that and always took them apart and cleaned everything, but you could do it in place.
If you give up and just scrape it off, buy a new "blanket" from Unicomp for $10. It is thin white latex instead of the thicker black rubber, and I think it is better.