Seattle, WA
you should have 70v on the under play-field molex when the magnet is "energized"
the center pin of the molex should show 70v to ground all the time
no positive voltage you have a fuse or a wire or molex on backbox that is damaged.
unlike sys7 games there is no "grounding" on the magnets
you can check Q14 tab short to ground, or power off ohm test from the non center pin on the molex to the tab.. should be 0 ohm or darn close. anything else you have a wire/plug problem for ground. or a dead transistor.
