I hope someone can help me.

I have an extremely old CRT attached to a Space Invaders B&W arcade cabinet.. There is no available schematic, that I can find. The flyback has died but there is no modern replacement, mainly because the documentation for the historical model is non existent. So I dont know the input or output voltages, I have no circuit diagram, and I cannot find anything to determine what its input/output parameters can be. I do have the old flyback, I know the monitor size, and I have the actual circuit.

The model is marked as "Toei GM-140 TV MONITOR". It was produced around 1979; or from 1976 onwards.

My question is this: Can one retro/reverse engineer or somehow determine what modern equivalent could replace a flyback in this circumstance. Is this possible?

Cheers in advance.