Hi,
Recently the left cannon on my STTNG started going into "Launch A Probe" mode randomly. So while playing a game, the cannon will start to rotate. I checked and cleaned the optos and they seem to be working fine. The obvious cause could be an intermittent short in the wring harness - but when I move or jiggle the harness it never triggers the problem. Could it still be something bad with the opto? Any other suggestions on how to diagnose or solve this problem?

On a related note, when the game first boots up, both my cannons use to go through a single rotation (and the kicker solenoid would fire). But now only the right cannon does this? Is it normal for the cannons to do this when the pin first powers up? Could this be related to the other problem?

Thanks!

Thanks for the suggestion to replace the harnesses. I purchased a pair from PinballHeaven (thePinballWizard also had them in stock). Hopefully this will solve the problem.

Fixed: Faulty opto receiver was the problem.