I have an iMac G3 (Indigo) that must have had like clear shipping tape put on it to hold something down at some point. Well it was taken off, and the tape came off, but the sticky adhesive is still on the outside of the plastic iMac case. Does anyone know of a good thing to use to get it off? I've tried goo-gone (kinda works), rubbing alcohol, and rubber rejuvenator (wiping that off with rubbing alcohol). Nothing seems to totally take it off. Any ideas?