Do not use brake fluid! It attacks several types of plastic and can melt it or cause it to become extremely brittle. Try a paint remover that’s safe for plastics. For really tough jobs I use a very small amount of non-acetone nail polish remover applied with a Q-tip and scrubbed with a toothbrush.
Are undecorated units THAT hard to find?
At the LHS I go to, undec shells are not always available and I’m sure there are a lot of modelers who don’t want to wait two or three weeks for an undec shell to arrive. I take what I can get. If it’s a pre-painted shell in a roadname I don’t use, I’ll usually strip it. Sometimes I just paint right over.
Even limited runs are gone. I tried to get some Undec engines with QSI sound and dcc a few years ago and decided not to worry about it after learning that they were all sold out at the time. So I would not worry about the undecs so much.
Having said that, one of my hobbyshops has a shelf full of undec rolling stock of all kinds but no engines in undec that I could see.
When I do a engine, I’ll just buy one with a very close paint that is easy to spray over with my colors and move on.
I think so. There don’t appear to be many of them around.