I have now started the hopefully not too long process of figuring out as much as I can about this monitor and its cable pin-out. I began by taking off the main board:
I discharged the HV anode just to make sure even though it had not been powered for a month at least. The circuit board had a different layout than the 5151 had, but it did have similar critical parts such as the 7406 which connects to many of the video input signals.
It took about 3-4 hours of probing with my multimeter and comparing to the 5151 schematics, but in the end I finally had a full pinout of the monitor.
Luckily, the monitor only requires 15V and 5V power, and in the 5151 manitor they were both generated from a 15V 1A source so it should not be very complicated to get working!