Hi guys,
just picked up a doctor who this weekend and the time expander gearbox was dead unfortunately, so I replaced the motor and gearbox. it's working fine now, but I'm only having the problem that when one ball is in the time expander locked at the begin position, there won't be a new ball at the shooter lane.. I can push the button to eject the ball and only the solenoid pops but nothing will happen because there ain't a ball there. what can I do ? what should I check?
Regards,
Dwight

Yes, there are 3 balls in the game trough switches are fully working and just to be sure i've resoldered them. wich opto's do you mean? when the first ball is in the time expander the pinball notices it, but he won't fire a new ball out.

Fixed it, the switches in the trough were stuck. I also found a bad transistor on the small pcb.