Miriam,
My son was a SM mechanic for 14 years. A lot of times when a machine would come in (usually the plastic wonders, but not always), they would take the machine apart and soak the shell in a mixture of water and Purple Power. Of course, you have to wait until the shell is dry before you can re-assemble it, but it's amazing what that stuff will clean off.
Obviously, you wouldn't use something like that for a machine with decals, but it sure does cut the nicotine smell and appearance.
Jeanette