Not sure if you tried this for what it's worth:
If the score motor continues to run:If the game has score reels, see the Score Reel section. If either of the two "zero position" switches on any score reel is out of adjustment, the score motor will continue to run.If the game does not have score reels, see the Stepper Unit section. If a stepper unit does not reset, the score motor can continue to run (actually this can happen on games with score reels too), because the game cannot reset the stepper to the zero position.If a Gottlieb game, make sure the score motor "brake" switch (a single switch on the score motor that has *no* wires attached to it!) is hitting the metal rod as the score motor turns. The purpose of this "brake" switch is to make sure the score motor stops at an exact home position and doesn't "over run", and continue running endlessly.Check the score motor's "home" switch. On Gottliebs usually at 1C or 4C, on Bally and Williams games the "home" switch is usually on switch stack #1. This switch is what turns off the score motor when it rotates to a "home" position every 120 or 180 degrees. Because of the score motor's electro-motive force (EMF) when the motor turns off, the score motor home switch gets a "blue arc" every rotation of the score motor. (Easy to see when the score motor rotates!) The blue arc is *twice* the powering voltage due to the EMF that occurs as the magnetic field of the motor collapses when the power is removed. This blue arc makes the home switch wear and pit easily, and go out of adjustment. If the home switch is out of adjustment or worn, this too can make the score motor to "over run" a home position, and perhap never stop or start running!
Found this on following site:
http://www.pinrepair.com/em/index3.htmHope you solve the problem. Any title with the word Bank is difficult to deal with.
