First- Laser Ball (not Lazer Ball) is a amazing pinball machine. I think it is the fastest wide-body pin.
Here is a link- repair guide for system 6-
https://pinwiki.com/wiki/index.php?title=Williams_System_3_-_7
Here is a link to the Laser Ball club-
https://pinside.com/pinball/forum/topic/laser-ball-club-watch-out-for-her-balls
Personally I would start with replacing the 40 pin connector between the two main boards. Great plains electronics sells replacement connectors.