So here's the thing my normally reliable space shuttle machine is not being so reliable, It had been working fine ,2 weeks ago in mid gameplay features started going down no credit button no kickers no ball release from the capture holes no way to start new game. There was a loose ground connected to the coin door after tightening problem solved. Played great for a week, then the same problem. I checked the ground again,added a washer tightened the hell out of it, problem solved. Yesterday same issue, I checked the ground and this time no effect, time to look for other culprits, where should I begin? I have limited technical experience, but want to learn. I have micrometer in hand, and should have some time over the weekend to address the issues. Any help would be appreciated

So after a lot of checking what I found is all the grounds are okay however none of the solenoids fire during solenoid test, after much searching found a bad diode on one of the solenoids. My question, would a single bad diode on the solenoid interfere with all of the other solenoids working on the machine?