Hi, I need your help in checking my thinking on this diagnosis. I am maintaining a BTDK Pro at a Ronald McDonald House in Milwaukee at the Children's Hospital. Kids love pinball, and are playing the heck out of it. Game has been there at least two years, only a few minor issues (broken plastics, solenoid wires fatigued off, burned bulbs, lots of grime).

Crane was reported as not moving. Balls were getting stuck as the crane was slightly off the home position.

Ran crane diagnostics, no motion at all.
Removed motor/gearbox, tried to move the large gear, no motion at all, not even a few thousands of an inch of rocking.
Chain off the gears, i could move the arm, and all optos check OK.
Put a meter on the motor terminals and activated the test. Meter showed voltage of 20VDC for a few seconds. Of course, no motion. This is repeatable.

So I think the opto electronics and drive circuits are functional, but i have a locked up gearbox or motor (could not take the time to separate the two and i will bet Stern doesn't sell them independently).

Removed the crane arm (square shaft design) and stored it in the cabinet so the kids can continue to play.

Let me know what you think.

Don