Interim report on my similar United Moon Glow. I have discovered the cause of the startup coil buzzing/locking/noise. The 100,000 point stepper was plagued by 70 years of grime and grease and hardly moved. At game startup, the wheel is supposed to be free to be reset to zero, motivated by a clock spring. I want to thoroughly clean this assembly, but for now, freed it up enough to allow the spring to make it hit the stop and silence. This stepper also needs calibration, as it currently resets to 900,000, not zero.
I have most playfield components working, except one of the corner trapezoid bumpers, though its switch is good, is not activating anything.
The ball trough gate solenoid is not being activated at game start, though the coil seems good.
Cleaning has been the best first step in remedying issues, but at this point it sure would be nice to have a schematic, to know what is supposed to activate what and to verify NO and NC positions of relays. It seems United only started offering schematics later on for their shuffle bowling games. I have found nothing for their pinballs.
Onward...
Added over 5 years ago:
I decided to start a new thread concerning Moon Glow work:
https://pinside.com/pinball/forum/topic/united-moon-glow-1948-early-flipper#post-5241607