[Arran]

With regard to checking the resistance of the transformer windings I now do that whenever possible as I have been burned a few times. I decided against buying a Canadian RCA A-23 on that basis, the difference between the two legs on the HV winding was something like 120 ohms, and whilst the set may have worked the transformer would probably start getting hot within about 15 minutes. On the Canadian Pye I also checked the transformer and it came through with a clean bill of health so I went ahead and got it.
  Basically you just have to look up what rectifier tube the set uses and measure between the plate pins at the rectifier tube socket, if it's a four pin tube it's easy, the small pins are always the plate pins, large are for the filament. On a 5Y4 the filament pins are pins 7 and 8, plates 3 and 5, the same is true with a 5X4. On a 5Y3 the filament pins are 2 and 8, plates 4 and 6, the same is true with a 5Z4, 5V4, and 5U4, this set uses a 5Z4 for some reason. You can measure between each plate pin and the chassis as well, even if there are resistors inbetween the center tap and the chassis both legs of the HV winding should measure pretty close to equal, within 40-50 Ohms of each other. I would also check the speaker field if you get a chance. Here is the schematic on Nostalgia Air:

http://www.nostalgiaair.org/pagesbymodel...014711.pdf

Regards
Arran