Okay, the 253's body has been removed, stripped of trim (except the handrails), then overnight in a bucket of diluted dishwashing soap. Usually this will remove all or most of the paint, but it doesn't seem to be working in this case. I'll leave it in there for another day or two, but probably going to turn to a purpose-made chemical stripper.
In the meantime, I inspected the chassis and motor, and all looks relatively good. This may have been rewired at some point, as the wiring looks like it has plastic-type insulation on it. I would have thought that, given its age, the wiring insulation might have been cloth. Regardless, the existing wiring now has some cracks in the insulation and should really be replaced. I might opt to rewrap it with some shrink-type plastic insulation I have here somewhere; haven't decided yet.
The good news is that when I put it on the test track, it ran nicely (even with cracked wiring and pick-up rollers in tough condition). It has a manual forward-reverse, and that worked fine as well. I gave the internals, especially the commutator, a shot from my stash of Radio Shack
Control/Contact Cleaner & Lubricant. Some folks say you shouldn't use the stuff, but I've had good luck with it.
The frame looks to be in good shape, so just a thorough cleaning and polish called for there.
Back to the body-work next. I might hit Sarge up for some assistance...his solder skills far exceed mine.