I'd look carefully at your 3-5 ball adjust jones plug first. Makes sure all the male/female connectors are clean and the wires are soldered on solidly.

I guess it could be something like an open where the red X is in the snippet below, but simplest thing is the Jones plug.

TA player unit (resized).JPG

Where did you “assign” the 3 ball setting? I have seen more than 1 pin have it where you had to go under the playfield and in the backbox for it to work correctly?

If it plays 3 ball okay with > 1 player doesn't that indicate the jones plug connection is okay, since that last ball function on the schematic is determined by that single plug wire? There are probably other pins on the jones plug but they would alter certain game features only.

Either contact rivet at position 8 on the player unit (at right of the red X) could have a broken wire at the wiring lug, or is not making contact with the wiper fingers due to wear/crud on the contact, or its wiper finger is dry/dirty/sticking.

frenchmarky - you're right about the Jones plug connection being good if multiple player games work correctly. Thanks. When I reply to these things at 7Am, my logic is sometimes questionable.