Quoted from llevine5:Thanks, will do. Just curious (being new to pinball); let's say the connection was somehow broken between the connector and the board. Why would plugging and unplugging then cause the series to reset? Is it because you are breaking the column/row matrix processing cycle, then reinstating it, so something in the ROM says "Hey, reset everything"??? I would have thought if the connection was broken, it wouldn't reset at all, but that's not the case.
I would also replace the diodes on those coils for the drop targets - I use 1N4004 I believe. The 'horseshoe' connectors were notoriously flaky as were the circuit boards, and you might even have a problem with the drop target guides, which I can 3D print.
I second shimmydisc 's suggestion on a replacement MPU/Driver board from RottenDog - MPU327. I was having a hell of a time.
I also second Robotworkshop 's suggestion on replacing connectors - the .156" connectors on the MPU, driver, power boards especially.
Also do yourself a solid and put an 8A fuse with holder inbetween one of the blue leads on the left bridge rectifier and one of the red leads on the right bridge rectifier (underneath the PSU, a little to the left I think). The reason is that you want to prevent the machine from catching fire. Literally.
Look up vid1900 's guide on Bullet-Proofing WMS system 3-6+, you'll be glad you did.