I further stripped down the game and discovered the probable ‘root cause’ this game stopped operating. Probably then sold in a job lot to a US operator and never got worked on. A gun solenoid that ‘fires’ one of the players gun was damaged somehow.
Not looking good, think this puppy is toast!
On a search on the internet I can get one to fit in the housing, it is nominally a 120 V unit. The game operates on 100 Volts so it’s close. The 50/60 HZ cycle is probably not an issue on these small sizes so I think this will work as a replacement. Will change both guns.