Well, I figured out what was wrong with the switch motor. I just didn't solder one of the wires on quite right. But then I got to thinking, the little switch I used as a limiter had this massive dead zone in the middle. So I built a new switch, which looks like a complete hackjob, and is, but works brilliantly. (It's the bit with the brass square.)
This left me with an orphaned SPST, which I connected to a bicolor LED from a computer monitor. I glued a little light pipe to the LED and stuck it through the foam. So, now, I've got a visual indication of which way the switch is pointing: green for straight on...
and red for diverging.
Now that I think of it, it really should be in some kind of signal bridge... maybe I'll move it later.
No progress on the engine or transfer table, though I think I've figured out how I'll do both.