Makvision 24.8" Tri-Mode Monitor Issues

[CoinDropper]

I have an atari area 51 cabinet and had to replace the monitor with a makvision 24.8"  tri-mode monitor due to a mishap during transport (rather ugly and upsetting). I am having issues with the horizontal sync on the monitor. I have adjusted as far as it will go and the screen is still too far to the left with about a 3-inch gap on the right side of the screen. Has anyone dealt with this or know how to fix the problem? It's driving me crazy! Also, I have to adjust every time I turn the game on, or when I go into test mode. I'm guessing it's a sync issue, but I wouldn't know where to start to correct. Any help would be greatly appreciated!