Okay...the good news is:
I replaced the mainshaft kicker gear, and the kicker clutch thingie today. The old clutch was in not the best shape, and the teeth definitely mesh and seat together way better on the new set. Once I got the gear off the shaft, I see that the kicker gear-teeth are not in the best shape. Not trashed or really bad, but certainly rounded off a bit. The gear in the cover, on the kicker shaft, is in great shape.
One tooth on the clutch was rounded off, but I'm not sure that would cause any skipping, although I'm sure it did not help. The bushing was not loose in the gear like I thought, but it was WAY too loose on the shaft. I think there was enough wobble to allow the not so well meshed clutch and kicker gear to disengage.
I also got the impression that possibly, the bushing was a little too long, and not letting the clutch and gear completely seat/mesh. But that's just a theory. The new gear and clutch certainly mesh better, and you can see they seat together better/deeper.
I'm saving putting the kicker cover on for another day, as a couple of things on it need attention. I'm thinking that the distance the kicker shaft gear sits in, from the cover, is important. (??) Was fun working in the 28 degree garage today! After I get this thing kicking right, I can get back to wiring, and then actually trying to start it. I'll build a fire in the stove when I do that, and devote a whole day to the process.