Still whacking away at this old jurassic park dragged from storage. I've discovered a new weird switch issue. It's very unlikely it's a cpu board problem, because it happens over two different cpu boards. Here's the deal: When the right-most trough switch is on, if any other trough switch is on, activating anything in the same row as the right-most switch also activates the same target in the other trough switches' row. So Trough right, switch 15, is green-red/white-violet. If it's activated, hitting trough 6 (#14, green-red/white-blue) and slam tilt (#7, green-brown/white-violet) will also activate Left Coin (#6, green-brown/white-blue). Weirdly, hitting trough right, the shooter lane, and another white-violet doesn't do anything odd. Neither does having any two other trough switches activated together. I thought maybe it was the diode on 15, so I replaced that. No... is it the switch itself? Replaced that, no help. Maybe the switches are somehow shorted on the trough? No, I removed trough 6 from the physical trough, still does it. Tried the diode on trough 6. Nope, still doing it. Maybe green-red is shorted to the trough? Remove green-red from every switch, stitch it back together, and still no luck! I've examined the other white-violet switches, and there is no obvious solder splatter or touching or whatnot. I can't think of what else it would be. Anyone have any ideas?

....I am so stupid. I never even thought of that. All fixed. I feel a bit better that my boss missed it too, and he's been doing this for 12 years.

Thank you very much Terryb, by the way. I would be so screwed without pinside.