Quoted from zacaj:
Did you replace and gap the switches on the lower flippers that control the upper switches?
I did, and I checked that a bunch of times...but what I didn't realize is the switch for the uppers are actually on the lowers (you mentioned this atop the thread but I misread it as the switch was at the buttons). This is my first older solid state so I'm still kinda figuring out what everything does. Realizing the upper flipper switch is basically an EOS switch on the lowers, I just changed the gap to be very tight rather than 1/8".
This fixed BOTH issues....now the upper flippers flip exactly with the lowers (I'm sure there's a tiny delay but it's not noticeable) and the upper right no longer jitters.
Hey RacingPin - jusy FYI, all that work you did isn't really necessary....just make the switch gap shorter on the lowers and they flip exactly like modern games with uppers.