I’ve been away from model railroading for twenty plus years and I’m coming back. My problem is that I want to renumber a couple of Athearn Genesis Diesel Engines, as well as an Overland factory painted diesel engine. I would like to know how to go about doing this, without messing up the factory paint job, be it brass or plastic. Thank You VERY MUCH, in advance for any assistance (HELP) in this matter.