I’m working on restoring a 1974 Bally Flip-Flop. It’s difficult to take photos showing progression since all of the work so far has been mechanical rehab: disassembling internal components, cleaning mechanisms, lubricating, adjusting, function-testing.
Detail on a score reel prior to rehab. Reels themselves are dirty and the mechanisms don’t actuate.
The disassembly process commences. Clean each score reel (and hope that you don’t wash off too much lettering). Burnish and adjust the switch for the 9-position. Clean the axles/pivots. Polish PCB contacts. Apply a dash of lube to each axle and pivot. Test the mechanism. Tweak spring tension as needed (typically pull 2-4 loops out to ensure reliability). Repeat 15x more for the rest of the score reels.
Now that you’ve gotten all the score reels clicking along properly, work on all the other components! Steppers need a rebuild just as extensive as the score reels (mercifully, no real need to clean the numbers). Relays need tuning. Broken wires need to be noted. Resistance on coils must be measured (some have likely burned up over time). Maybe you want to plan on replacing all those light sockets. You might also want to track down a font for re-lettering the score reels.