So got a new kind of job in, runs simplex on preprinted shells, 9.25 x 17.25" Feeder A1 lower has the paper jumping inboard/outboard by a centimeter. Completely randomized. Feeder A2 lower feeds it pretty straight, a little bit of wobble in the process direction. An occasional IB/OB jump every 100 sheets or so, but only by a few millimeters. Definitely figure something's wrong with my A1 lower. To keep this short-ish, turns out that any paper that's got a lead edge of 9-10 inches runs a risk of hitting the most-inboard set of rollers along the paper path wrong, particularly the registration steering wheels. It either misses them completely, get's gripped by them, or anything in between, bouncing them all over. Had the shells trimmed down to 8.75" and runs like a dream. And apparently my A2 feeder set runs about 5mm more outboard than my A1 feeder, so that's why it behaved, sort of.