When things don't make sense, suspect power. Without clean, reliable power, the pinball could show as having all kinds of intermittent problems.

For a long time these Whitestar boards haven't been too troublesome, but I've had three in the last few months that to keep from resetting I've had to replace CN2 on the bottom of the CPU board.

I replaced the pins, and used crimp-and-stuff trifurcons for the plug.

I definitely had problems on one of these Whitestar games with J16 on the main power board. (This is the main power distribution plug, it's right under the CN2 connector on the CPU board.) Cracked solder connections, but also heat-tarnished pins. Once again, replace this connector pins and plugs, with trifurcon.

Since I've done these fixes, the three machines in question haven't shown any problems.

Once you are sure you've improved the power to the boards, I'd do a deep dive on this switch and it's associated wiring. Anything pinched, touching, insulation rubbed off? Any way for the switch contacts to short out to the metal around them? I'd probably consider replacing the switch and it's diode just in case.

When this switch activates, does it turn on a light that might have a compromised or dead-shorted socket that robs power from the system causing a board reset?

Test the lamps, the switches.

Is it completely consistent? It does a reset every time and you can reliably make it happen? Or is it only once in a while, but you notice it when you hit the bank switch?

It's gotta be something, and you've done the normal things.

Let us know what happens here.