I don't have the schematic for your machine, but the only other thing you can check
is the switches in the Start Relay, but chances are slim the problem would be there.
If you look at the Frame Unit's step up circuitry in the schematics, I think you'll find
the Player Up Reset Relay is one of the first to be in the circuitry near the Frame Step Up
coil. Then near by, the Score Motor switch which suppose to be normally open, and then
the circuitry breaks away in a couple directions, but if that score motor switch is open, it
breaks the circuit to the Frame Unit. You'll see where it ties in the Frame Unit's wiper itself,
but that's after the open switch on the score motor. Are you sure the solder tabs aren't
touching, or any type of metal particles aren't causing problems?
Are you able to locate the exact set of switches on the Score Motor that fires the Frame
Unit's Step Up coil?