Hopefully, Titch's long-press suggestion will work, but if not . . .
Looking into the manual further, I found the S1 test switch on the PCB (pages 37 and 30) that you mentioned was broken off.
It's the sliding switch above the JAMMA connector and disc capacitors in this pic, right?
If something hit that switch hard enough to break it off, there may be other damage to the PCB like broken traces nearby.
Also, are you sure you used the right type of replacement switch?
- Substituting an SPST for an SPDT could cause a problem, depending on how things are connected.
- I don't have the actual PCB or a PCB schematic to check, so this is just speculation.
I was able to control Volume + and Volume - by attaching some wires to the header pins and touching ground. I would assume TEST should do the same for #15 on the board.
The volume controls work like typical "active low" circuits -- applying ground triggers the output.
Grounding JAMMA #15
should similarly trigger test mode, but if it doesn't, that suggests that the fault is somewhere on the path leading from the ground connection on the non-PCB test switch, through the non-PCB test switch, JAMMA wire #15, JAMMA edge connector, PCB edge connector, S1 (test switch on the PCB), and the PCB traces leading to the test mode input, wherever that is on the PCB.
- Not sure if S1 is wired in parallel with the JAMMA wire 15 path or in series with it.
Scott