Robotron help needed

Hi Everyone, I'm experiencing a problem with my Williams Robotron
game. The game is in a Jamma cabinet and was working perfectly for
the last couple years. After a recent power outage, I powered up the
game and got a scrambled mess on the screen. It looks like the
monitor isn't syncing up and the board gives me a 131 error. I have a
Stargate board that I use in the same cabinet with the same power
supply, I installed it and it also is doing the same thing. I can
hear the Robotron making noises, but can't tell what's on screen at
all. I tried hooking up a newer Jamma board to the cabinet and it was
able to sync with the monitor, so I know the monitor isn't bad. I
tested the power supply at the board input and it was slightly low at
+4.7V so I adjusted it to +4.98V, but now the other two are slightly
high at +12.8V and -5.6V. Could it be the power supply that's to
blame for all this? Are these boards sets extremely sensitive to
voltage variation? What else could be the problem? BTW, I switched
the RAM chip from location 1-3 with 1-8 and it didn't change
anything. Both boards are giving me the same 1-3-1 error. The boards
have the cut jumper mod to make a composite video sync and have always
worked fine in the exact set up they're in now. Help!