Quoted from TimStevens:I also tried the method suggested there of shorting the tab on the transistor to ground to fire the coil. It did not fire the coil.
So, I replaced that transistor (Q71), but it still did not solve the problem.
You likely have a break in the ground wire to the coil. While shorting the tab on the driver transistor does not do anything to test the transistor, it does verify that the coil is getting power and that the wiring is good. Also, check the wiring on the coil bobbin to the lugs, sometimes it breaks. That one you just unwrap a little wire from the coil and resolder it to the lug, sometimes you have to sand off the enamel coating to get it to stick/conduct.
Check for voltage at the coil (dmm +dc on either lug, dmm - on any convenient ground i.e. the cabinet braid). Then check for a break in the wiring.
If you're missing voltage you might have a wiring fault upstream of the coil, tug on each coil's wiring gently. If you have no continuity back to the board you need to trace that out and fix it.
As you noted, the 2 switches that stick up through the playfield are the activation switches, they send ground to some logic gates which eventually fire the transistor, which fires the coil. The switch underneath has nothing to do with activation, it's the scoring switch for later on.