The red/yellow hole lights are controlled by a make/break switch on the Alternating relay (A).

The Alternating relay is controlled by a switch on the 00-90 Unit relay (AX).

The AX relay is an 'AS' style 'mini stepper'. Chance are good that it's gummed up and not able to step freely, so may need a rebuild/cleaning/lube. But it's activated by a switch closing on the M relay (so whenever 100 points are scored), or by switch P3E on the Player Unit closing.

Great - glad you got it sorted out. Enjoy the game.

Some of us like to keep things original when feasible; it's not a reversible change without swapping back in original, unmodified parts. It looks bad to have the edges cut and the filings make a mess, and it would have been faster to just loosen the screws and replace all the targets at once (with a little practice).

Personally, I don't see the point in going this route; the mod really isn't necessary, and ruins a perfectly good original part to try and save a very little amount of time. Drop targets don't break so frequently as to expect to need to replace the same ones repeatedly.

But, it has nothing to do with playing the games of course. It only makes collectors (like me) cringe.

Opinions on the matter differ of course...