Hi RetiredPinman
a vague theory - the Score-Motor-INDEX-Wheel-Switch (Make-and-Brake) , SCM-Ind-D: When the Motor starts to run: Yes, the "Make-Part" of the switch closes --- in doubt: Does the BRAKE-Part of the switch (SCM-Ind-D) truely opens ?
Look in the ipdb-schematics - at schematics-A/B-14/15 is the drawing of the Score-Motor-Index-Wheel. NICE - the Switch-D is the outmost / topmost switch --- You should get to it.
Have the pin toggled-off, line cord unplugged (Safety reasons) --- turn by hand the Nylon wheels of the Score-Motor a bit - Switchstack on Index-Wheel does actuate --- question: Does the BRAKE-Part of SCM-Ind-D TRUELY opens ?

Nearby in the schematics - at schematics-14-C/D/E You see this M&B-Switch-SCM-Ind-D and the wiring to "make the Bonus-Relay pull".
(If the fault is somewhere else: We must dig-in deeper into the (I do not love the feature): EVERY new ball starts with one bonus given.) Greetings Rolf

Hi RetiredPinman
in post-2 I asked about the Score-Motor-Switch "Index-Wheel-Switch-D, Brake-Part of the switch" --- the Brake-Part must open when the motor begins a turn - and stay open the rest of the turn. Greetings Rolf