Another trick, while in test, 'thump' the playfield with the side of your fist lightly.

That should rule out (or aggravate) any vibration induced issues.

Also keep in mind the switch you are looking at may not be the one giving you issues. Having it in switch test mode while thumping will pop up the number of the switch that is causing issues, and that could be some random switch hidden behind a rubber that could be adjusted too close.

Cool cool.

Usually it's the resetting of bank targets vibration that will do that on game start. Your lucky it isn't an old System 80 Gottlieb, they won't finish power up self test if a switch is stuck and it can be a pain in the butt to find.