Quoted from Its_me_aj:1. The only issues I have left now are flickering GI, 2. a weak upper flipper after rebuild, 3. and the first diverter rejects the ball and sends it back down the ramp every once in a while
1. Are you using LEDs for the GI? If so, is the flickering occurring only when a solenoid is firing?
If yes to both, then that's normal. The two GI rely boards are designed for incandescent bulbs. You will need to get modern rely boards that work with LED lights to get rid of the flicker.
2. I would check the connectors on the high current board.
3. Also normal! My Rollergames and the one I used to play at the arcade both do the same thing. Sometimes the diverter just acts like a bat and connects with the ball perfectly.