IT'S UP AND RUNNING!
Yesterday I wet sanded the platen with 320, 400, 600 & 1200, then used "Photofinish Darkroom Cleaner". After that, I cleaned it with wet rags until there was no black residue on the rags, then wiped it down with alcohol. I reassembled it & powered up. I had to do a bit of adjusting on the thermostat by bending the bi-metal strip a little, but it's almost right on now. It seems to hold 180 degrees within 3 or 4 degrees. The meat thermometer I have only goes to 190, so I'll have to find one that reads higher to check higher temps, but I think it'll be ok.