That's great but the diodes are not what usually fails on a classic Bally. Nearly 90% of the time, it's some of the disc capacitors that fail, not diodes. Bally used some very low quality caps back in the day. Use the switch test along with the chart above to determine that ONLY ONE switch # is triggered when you test each switch in the game. I fought a problem on my EBD for years and it was only sorted out after getting 4 or 5 shorted disc caps removed.

Right, switch test would reveal the problem simply looking at 2nd pic. in post#7 and with no tools in about 5 seconds. Typically, people new at pinball repair do not realize how the switch test can help solve things very quickly. Learning how to use that test is so important with early Bally machines. Most people that own these machines don't even realize that there is a SWITCH TEST.