It could be just that the monitor is fried, or needs a new set of capacitors installed (a cap-kit as they are called). But it also needs a good cleaning, and who knows if there are any deep gouges in the finish, etc.
PS: Working on Arcade Monitors can kill you. No Joke, you dont go messing around near the back of one, ever. You'd have to hire a TV repairman or someone who repairs monitors to mess with an arcade monitor....lest you run the risk of enough amps and voltage to hurt you really really bad, or worse.
Or the PCB board itself could be bad....in which case you'd need to buy another working Robocop PCB off ebay and swap chips, or just swap out the board..
In other words: Its alot of money to spend for freakin Robocop (a game that gets boring after about 5 min). Now if you gutted the thing and turned it into a MAME cab, it would be a nice cabinet to use....it has that rounded marquee (the part up top with the ROBOCOP banner on it)....get some custom printed MAME marquee and replace it.
PS: They made a nearly identical version for the Amiga computer, also by Ocean.