Just happened to turn on Ms. Pac for some night time play (as she's been so neglected for a few weeks) and found that the blue was all but sucked out of the screen. It's set to free play, so top of the Midway logo is black. I read online that this issue could be the monitor or the "Blue output edge connector pin U is grounded." The monitor looks to be old but had a cap kit installed on it from the company that was selling it at MGC. Other than that the game works great.
Reading up it seems like the edge connectors (where I'm assuming this "pin u" is located) get dirty or burnt out. When I get a chance I'll attempt to clean it but any other suggestions would be appreciated.