Good news! Well, sort of. I found out why my Robotron wasn't working. The CPU board has a problem. I swapped the CPU board in my Stargate with the Robotron one and now my Robotron is working again! The problem is, now my Stargate doesn't work. So I will have to diagnose the problem with the CPU board and fix that.
If anyone has any clue what might be wrong with it, drop me an @EMAIL@. The symptoms is that when going into the diagnostics, it shows that all controls for Player 1, Player 2, and Player 2 Start (NOT player 1 start), are stuck "ON".
I replaced the fuse block on my MsPac and all I can say is WOW! It's like I gave the monitor a cap kit! Bright crisp screen now, with ZERO hum bar! Next thing to replace is the edge connector so that the game doesn't reset during play.