I compared the needle bar area and both seem to be the same -- I measured with a 6" metal ruler and the clamps and marks are in the same places. It doesn't look as if any of the screws have been messed with. They both look the same when I move the hand wheel and have the take up lever in the same position. Of course, it could still need adjustment but for the time being it is close enough that it shouldn't be what is causing the stiffness.
I have pdfs of both the adjusters manual & service manual but both seem to tell you how to make adjustments and replace parts but not really what the symptoms are to need those adjustments or servicing. Again I found the opposite scenario where it slows down after sewing for a while. It seems to indicate that it is a result of the dissimilar metals having different expansion rates. Heat also helps make grease and oil more fluid. I've tried to approach this with obvious (remove threads) and easy (clean & oil/lube) solutions without messing up something else.
I have oiled and let sit every which way. I thought that by running it once it moved and fresh oil that it would flush any old stuff out. What limited experience I've had that has been the case. I have a 1902 15K that was frozen and it took a couple of days (in black trash bag in sun) before it loosened enough to move the hand wheel and after oiling it well -- it is fine. That is what I thought would happen with this one. I just don't know what to do next.
Janey - Neat people never make the exciting discoveries I do.