Thanks Mike! I'll need to find that gate again. Sadly, the one mailed to me appears to have come out of the envelope in transit, so it never arrived. One side of the envelope seal came undone, so it was simply empty. If anyone else out there has one, please let me know. Otherwise I'll try to find one or make one I guess?

Still waiting on the parts for the board work; hopefully arriving in the next day or two.

Success! Just finished replacing the bad Q12 (2N3904) transistor and that ended up being the issue. I really thought it would be a chip issue, but nope, replacing that transistor worked.

All the problem switches now function as designed (I had to reconnect all the diodes that the former owner cut on each switch). Game plays 95%... I'm just missing one thing... the gate for the space shuttle nose area. If anyone has one, or knows where to get one, please let me know. A picture of it is shown in post #50 of this thread, for reference.

Thanks to all for their help on this!

Thanks, sadly I didn't see it there when I searched using the "by game" feature a while ago. As you can see in Mike's pic earlier, it's an odd shape.