Well If it's just the turntable thats hot, follow its power wires and see what you find. There may be a capacitor up there. I'll bet, though that the turnatble, tuner and amp are grounded together. If thats true, the leakage could be coming from any of the three. It could even be the motor, but I'll bet its a capacitor.
The favorite thing for cleaning contacts around here is Caig Deoxit. I'd stay away from sandpaper at least for now.
I dont know what an appropriate lubricant would be.
Good luck!
John