Back of the disk,
Wash first,
Tap dry a bit,
Put a bit of toothpaste on,
Smear over the back of the disk,
Wash off,
Tap dry first, then dry with a towel (NOT A RUFF ONE! It will make it even worse.), and the back probably got wet too, so dry that too.
This is how I got my friends THUG2 back to work.
Works 85% of the time. Worth a try anyways.