[Arran]

The ballast is probably still good because it's main function is to drop the line voltage down for the tube heaters, especially if the set is used in places with 230-240 line voltage. So on 120 volts the ballast only has to drop 13.5 volts, as well as powering the pilot lamp bulb. With regard to the wiring did they use rubber/gutta perch covered wire or did they use the more modern vinyl wire? I have a Canadian model with a similar chassis called a 55T, also with 8 tubes, but it's an AC only transformer set with 6.3 volt tubes, the front end circuitry appears to be the same, the difference is that the 55T uses a pair of #42s and a type #80.
Regards
Arran