I am helping a friend with this machine and the schematics on ipdb are hard for me to read. Can someone tell me which transistor is likely the culprit?

I think that it is Q10 which is a tip 120. I also believe that it is what drives pin 8 on the 2J12 connector.

A verification would be appreciated.

As an update checked q10 and its pre driver and both test good as do neighboring tip 102s and pre drivers.

Any suggestions on where to look next.

As an update, here is what I saw when I went to my friends house to help him with the Gorgar:

The Q10 transistor (tip 102) and the pre driver have previously been replaced, as has the right slingshot coil. Presumably this problem has popped up previously and someone replaced all 3 items. That didn't work.

So, they presumably pulled the blue wire on connector 2J12 (pin 8 ) for that solenoid and sold the machine to my friend (a newbie with the itch since he has amassed 10 already over the last year).

I tested Q10 and the predriver as well as the coil's diode and they all tested within spec and similar to neighboring components.

I also pulled the 2N11 connector, which is the switch inputs, then re-connected the blue, pin 8 wire on 2J12, and the coil immediately locked on.

I believe that I have ruled out a bad switch, coil diode, switch diode, driver trans and pre-driver trans.

I suspect that the problem lies on the MPU/power driver board. So on vid's list above it would seem that it is a bad 7402 or bad PIA.

Any indication which component those two items are?

Thanks all!