Remove all the hacks, fix original problem that hack was supposed to "fix". Most likely that is 5V-adapter that feeds MPU-board because Driver board is fried and can't keep up solid 5V line (=assumption). This means that DB might have problems with other voltages also and needs to be overhauled. Start with that. Fried coil is most likely shorted driver transistor (or pre-driver), replace both. Also test other components on that string also (resistors, diode etc.). I had T2 which had over 20 burnt resistors in different solenoid-circuits causing those to hang. Transistors were ok, it is still unknown to me what could cause that. But easy fix after other modifications were removed.

And what comes to those switch-errors, check switches first (wires, diodes, actual switch). Seems that your game has pretty high miles on it so it's pretty common that those switches fails at some point. If errors not found, check MPU about battery corrosion etc.

Diodes are in the Driver Board at WPC, not in the coils. But indeed those are there.