I bought a United Brass Hudson this week on vacation and it needs to be cleaned and polished. HOW? It is from around 1965 to 1975 era.
Remove the motor and gearbox, and sandblast it. OR, dip the whole thing in an ultrasonic cleaner.
As for “polishing”, that’s up to you, but I really wouldn’t bother. I’ve only run across a few brass engines from post 1970 or so that were bare metal. Most have a layer of gold paint added to them.