We had two NSM (I call them NFG) jukes on our route back in the day. They were nothing but trouble and we had almost daily service calls on them. The special cable between the mechanism and the control board would develop breaks inside the cable. Amplifiers were constantly failing. Sometimes the...
I thought I had pictures of the sound board, but I guess I never took any of it. Our Mini Baseball machine is on location at the Olympia Pinball Museum here in town.
For reliability, the Dynamo is tops. Dynamo had bought out the original Brunswick air hockey designs years ago. Many operators use Dynamo air hockey games on their routes.
Looks to be similar to an American Shuffleboard score unit of the era. Perhaps the American Shuffleboard repair information/schematics may help?
https://arcarc.xmission.com/PDF_Shuffler/American_Shuffleboard/
My experience with electronic ballasts in arcade game usage is they fail frequently after about 3 months. The ones I had were typically shorted internally when they went bad. I replaced them with conventional magnetic ballasts and starters. No more troubles. :)
The 3100 has a pretty whimpy amplifier. Shouldn't be too hard to find a transformer to operate it. Have you checked with Victory Glass Company and Antique Electronic Supply?
That could have been the only wire they could get at the time the machine was manufactured. Remember, phototubes operate on about 90 volts DC so watch that you don't get zapped.