Hi all. This one has me stumped and I could use a hand on a new-to-me original AFM:

When I power the game on, the ball launch coil will fire twice in succession. It happens right after the lighting comes on, before the speaker tone sounds, and before the other balls are kicked out of the SOL scoop, saucer trough etc. It happens weather or not there are balls in the trough. It is also seemingly random. It usually does it but sometimes not, and I can't recreate the scenario in which it does not.

Thinking it was a switch matrix issue to do with the shooter lane switch, I replaced all the diodes on the switches in the corresponding row and column: shooter lane, right return (inlane), left outlane, left top lane, right top lane, ma"R"tian target, & center trough. The switches in the same column I have not messed with yet are: plum bob tilt, start button, & launch button. Could one of these be the culprit?

I cleaned and tested all trough optos.

However when I disconnect J212, J205, J206, & J208 from the CPU, the problem persists. That rules out a switch matrix issue, correct?

Thinking it may be a shorted coil, I swapped it out with the knocker coil (same type).

Otherwise the game plays and acts totally normal. No switch issues, no issues feeding & launching balls (also during multiballs)...

That's how far I've gotten, any help would be greatly appreciated. Thanks guys!

Thanks for the response. The coil still fires with the pf in the upright position. No burn marks on the coil brackets…

Thanks for the info. I can’t speak with the previous owner as the game was sold to me by a gentleman who had it wrapped up in a warehouse and had been storing it for the owner for years.
I did a factory reset, still having the issue. Will order a new ROM now and hope for the best. I’ll report my findings.

SOLVED: Apparently upgrading the game ROM solved the issue. No more coil firing when I power the game on. Thanks @kjl!