Short the "position 9" switch to verify it does not advance. If it does, fix the problem with the switch stack. If not, use the wiring diagram to figure out what switch is open or wire is broken. Use standard electrical troubleshooting techniques.

I'm having trouble with my TEN THOUSANDS reel on Player 3.
When I start a game, even a One Player game , after about 5-6 seconds, that reel will increment by one just with the game sitting before I shoot a ball..

I've watched it click from a 6 to a 7..turn off pin. turn on/press start..5-6 seconds 7 clicks to an 8 before ball is even shot.even the 9 will click to a 0.

Any ideas..anyone?
EDIT:
I must say now that the Player 3 TEN THOUSANDS reel is at 0, the game starts as it should and doesn't appear to want to "ghost" move to the next digit by itself. (of course until it's a 1, then it'll do it all again till 0 comes up again.

This is generally a problem on the score reel relays. In addition to the 9 position switch, there's a switch on each relay that sends power to the next reel up to step that reel when it goes back to zero. Both the 9 position and this switch have to be closed or the next reel up won't move.

Hit the nail on the head EMsINKC. The switch on that TENS reel that sends the power to the next reel wasn't gapped open enough so it barely opened when the plunger was pulled into the coil. I looked at another score reel relay to compare and opened up the gap ever so slightly and all is good now.

Thanks also Mr Bally!

I just LOVE an EM that works correctly!!!!