Newby Repair Question - Taito S.C.I. - Special Criminal Investigation

[Exzert]

So somebody is selling the Taito S.C.I. - Special Criminal Investigation arcade machine for cheap because it was having issues.  I really want to learn how to fix these broken machines but I figured I'd ask some people who knew much more than I for I really don't know what I'm getting myself into.  This is what the owner has to say about the machine: 

"Complete machine and does power on.

Most time powers on to garbage on screen, sometimes after messing with connectors, it does kinda work."

Somebody is selling an old PCB on ebay for this game that was removed from it's machine 2-3 years ago and put into storage.  It worked when it was taken out.  I'm not really sure if it could be the pcb or the connections?  I'm not really sure about the connections for these games or how they work.. ANY information or advice at all would be greatly appreciated!  Thanks