Have a whirlwind that has been having some ball through switch issues. When I first got it a few months ago it wouldn't start a game and said "pinball missing" despite three balls being in the game. I found an internally broken wire between the outhole and ball through #3 and replaced it. That seemed to solve most of the problems. However, the "pinball missing" issue still happens occasionally, but if I turn the machine off and come back in a couple hours or days the problem often seems to have magically vanished. Today I investigated further and found the ball through #2 and #3 switches not working (they're in the same column) in the switch edges test. After a lot of messing around, the ball through #3 has begun working. I think this was a cold solder joint. The ball through #2 is still not working. I've reflowed the solder on each lead of the switch, replaced the diode, checked for continuity between other switches in its respective column and row (tested fine) and checked the switch itself (also tested fine). What am I missing? Below is a link to the switch matrix.
https://www.pinitech.com/switch_database.php?name=Williams_Whirlwind
Thanks in advance.