Can a solenoid transistor go out then come back again?

I'm working on my Stern Wild Fyre - The other day I was playing it and everything was working fine. Then my wife came in and wanted to play. While she was playing I noticed the 10K digits were all flickering. I turned it off while we ate diner. After diner I turned it on to check the flickering and it didn't flicker. I played a few games and it working fine again. I left it on while I did some other things. After a while I noticed it was flickering again. I turned it off then on to reboot and it stuck on the fifth flash. Bad PIA? The next day I replaced the PIA's with the only ones I had - they're used but were working in a spare board. I turned it on and everything seemed to work again. I left it on for almost 2 hours - and it was OK.

I turned it on today to play a few games and it worked fine. I left it on while I cleaned the shop and played it a few times - then it wouldn't kick the ball out of the outhole. I went into solenoid test and the outhole solenoid wouldn't fire. I turned it off while I checked the schematic for the outhole transistor. When I turned it back on again it was working fine again.

Would a bad PIA cause this kind of problem or could a transistor?

Thanks

Bob

The MPU is near prefect. New connectors and headers.

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Thanks pinballplus,

I've had the game on most of the day and play it every few minutes - so far it's been working fine all day - hasn't missed a beat. The driver board has new headers and connectors but I think I might reflow the solder on all the transistors just to be sure.

I hate when I have everything working then someone comes in to play and it acts up.

Bob