I have an old Lionel GP9, which has been stored away sine 1960. So I’ve started cleaning it up. When I use isoprpol alcohol to clean up the plastic I’m left with a residue which pronounces the dirt and dust.
I need suggestions about the proper chemical for cleanup of an old part.
It sounds like the paint finish is reacting to the alcohol. If the problem is just dirt, you could try a mild solution of soap and water with an old toothbrush. Just take the shell off the mechanism! You don’t want to dunk the electricals!