..do you have a wire brush on a bench grnder? That would do the trick in short order.
In situations like you mentioned I've usually been, with a little elbow grease, to tighten them up. I did this on the ones of my 52panel.
Running a die up on the threads should not hurt it...although there are thread "chasers" as I call them, just to clean up the threads and not "cut" them any.
If still fresh paint would a little paint thinner cut the paint off?
