Okay I'm far from any sort of expert on original hardware so not sure on mixing and matching monitor, chassis and PCB but original games were developed for a specific resolution. The screenshot you have says its a 1995 game but you're running it on a really old 14" 1981 monitor.
I hope experts chime in but for me this is questionable.
The chassis should come with at least 4 may be 5 adjustment dials. One of those with be horizontal width and another horizontal position. Adjust both of these and see what the result is.
Cheers,
Brad