The game made it to the show OK and was running OK during Thursdays setup. On Friday I noticed there was no picture and began to investigate. Initial investigation found the monitor running but there was no +5V at the game PCB. The game uses a switched mode power supply that I wondered if it had shut down so I power cycled the machine and it did indeed come up running OK again. A short while later the power supply shut down again, however. I had no spare power supply for this machine and so the game was pulled from the show :(
Since the Tokin PSU terminal connectors match the common garden variety JAMMA power supply I considered simply replacing the Tokin one with a new one but decided first to give it a look over and potentially fit a cap kit. Tokin is a NEC brand, built in Japan and intended for the 100V internal voltage this cab used. It had also been running without issue since I bought the cab 20 years ago. That said, there were no schematics I could find online for this model making repair difficult.
Dissembling the PCB from the frame and inspection found a cracked solder joint on one of the power transistors. It looked like the PCB had a layout defect that misplaced one of the holes for the transistor and a leg had been bent over to mate with the pad that had now cracked open. There were a couple of other suspect solder joints that I also touched up.
I changed the orientation of the PSU from vertical with PCB facing away from the back to horizontal to allow better access to the voltage adjustment pots & fuse. I'm guessing the original awkward access installation was to keep hands away from the high voltages on the PSU. On power on the game came up OK and ran for a few hours without issue. Fingers crossed for another trouble free 20 years :)