Well alrighty then.
The machine is 100% functional. Woohooo!
That 1st/3rd/ player scoring thing isn't really figured out, but I got it to work anyway. What I mean is that with the player 1 "ones" score reel installed normally it does the screwy thing, but when I slipped it out of the slot it worked as it was supposed to ! So it seems to be some kind of grounding issue. To make it work, I simply installed it back into position with some strips of mylar to insulate the reel from the mount and screwed it in  place with nylon screws so it stays isolated from the rest. So I don't know what's going on there but it works OK with the hack. Good enough for now.
The broken gear tooth thing seems to be working OK for now. I played over 75 frames last night and it's still OK as the pins are still raising and lowering as it's supposed to.
All the bulbs are working.... What else....
Games appear to score properly...
All the sections are properly bolted together....
Basically, it's a GO for Christmas day. So today I'll be hauling it over there and setting it up. I'll try to make a short movie of it in operation and upload it.