took mine apart last weekend to finally fix the ball sticking on the magnet and also the double flipping triggering in vengance 2. here's my observations as i can't find the other thread.
Tried all the usual twisting wires & swapping boards. here's what i did

Removed the guides with the opto's attached, reflowed the solder but noticed that one of the mountings was not at 90 degrees and therefore not correctly aiming the opto. this pretty much fixed the sticking ball issue but i found improvement by going into game settings #2 and setting disable magnet to yes. Bizarrely it doesn't disable it but appears to let go properly in vengance.

Went into switch test and mashed the flippers, you could see the bottom opto sometimes briefly triggering. It looks like it's the connector end as the don't securely fit. Took the board off and mounted it on rubbers which has fixed it. Seems a vibration issue.

All working now for the first time since i unboxed it!

honestly, it's PITA. especially the left side but I did it all in a couple of hours.

as i posted above, try mounting the board on rubber feet. It looked like a vibration issue to me.

tewaked mine by re-aiming the beam, had to bend the bracket it mounts to. Works perfectly now.

Back in the club for the third time! LE incoming.