Quoted from dogman:
Here is a great tip for anyone that is experiencing issues with their game and cannot put a finger on it.
What I like to do when I am working on an EM game for a customer is to quickly determine what the problem is.
To do this on a mechanical game simply remove the playfield from the game by removing the jones plugs.
Do this with the power off and carefully remove them. You can leave the playfield in or take it out of the machine.
Then turn the game on and see if the score motor stops rotating or the component that was energized is no longer functioning.
This way we determine: Is it playfield or cabinet. If the action continues we have a cabinet issue, if the action stops, we have a playfield issue.
9 times out of 10 it is something so easy and we try so hard to figure that its something so difficult.
Agreed, I often do this. I not only confirms the problem is not playfield related, it makes life easier when working on the motor board.