I have a 3003b CoCo 1 (the white one) with the melty keyboard. A few of the keys do not work. On a few of them, there appears to be a slimy substance that I've cleaned from the surface. The badge on the top of the case is mushy, so I can only assume someone used a cleaner on it and it got down into the keyboard.
This keyboard used folded mylar sheets with a separator sheet. I'll be taking the keyboard apart next week to inspect it. What's the best cleaner to use on these types without damaging the mylar or the material the traces are made out of?