Any tips on servicing Marchant calculators?

I just picked one up today. I don't know what kind of shape it's in. The salesman said, "Why wouldn't it be in working order?" -- I can think of many answers to that question and (as I know from reading the list) it's always a good idea to check something out before wrecking it by turning it on. My model is a tasteful shade of dark green, with "MARCHANT" in gold Art Deco- ish letters. I think it's one of the earlier electtric models (it may be one produced from 1939-1945). I'd like to know if there is any simple cleaning up I can do. What's the best way to clean the plastic exterior? Is it possible to operate the mechanism by hand? (The machine didn't come with a power cord. It's in an "unstable" state -- some dials are in intermediate positions, and some multiplier keys are engaged. So it might be a good idea to clear everything.) And does anyone have advice on repairs? I've taken off some of the panels and I was rather intimidated by the mechanical complexity. Then I did some reading on the Web and learned about the insane mechanisms these things use for speed (proportional gearing to handle the carries, tiny differentials, three drive- shafts, the division mechanism which has an analog comparator, etc.) and now I'm *really* intimidated. :) If there are any repairmen in the Seattle area, I'd love to hear about it. (The same guy had a Comptometer which I wish I had bought -- a friend of his apparently has it, and when she opens her store in November it will surely go for 1.5 to 3 times the price he was charging.) Thanks, -- Derek