[cathoderay57]

Visually the mains transformer looks OK - I've seen a lot worse! Usually if the transformer has had a very hard time or has winding shorts there is evidence of leaked melted wax and I can't see any on yours. You're sensible to do dc resistance checks but don't get too hung up over it; providing the HT winding isn't open circuit I would be inclined to disconnect the rectifier cathode from the HT reservoir capacitor then power it up and measure the dc voltage at the rectifier cathode. So long as it is somewhere in the order of 180-200 volts and there is no smoke or bubbling wax from the transformer then all should be well. Once you connect a replacement reservoir cap the HT voltage at the cathode should rise to the value quoted in the service sheets. If you are still using the original HT cap and the set still hums with the volume control at zero then the HT cap is almost certainly unserviceable and will need to be replaced. Cheers, Jerry