I'm having an issue where the machine pops two balls on the playfield on startup. i went into the switch test and found whenever opto 4 or opto 1 get tripped it quickly registers opto 1 and flips to and stays reading opto 4 for on the test. i changed the sending and receiving optos for both boards on 1 and 4 out of desperation , not surprisingly it didn't help . i traced through the wires and dont see them pinched together anywhere . I'm needing a little direction on what to check next .