Power Transformer Kaput ???

[LinuxGuru]

I have Pioneer SM-83 vacuum tube amplifier, and few days ago I have noticed smell of burning oil or whatever else material used for paper impregnation. Pioneer power transformer uses a lot of layers of oil-impregnated paper between layers of winding (this is 120/220V power transformer, not audio output).

Amplifier always run very hot, but I never noticed any smell except stream of hot air.

I measured output voltage, it was normal. However, when idle, amplifier have drawn only 80mA from 220V power outlet (below 18W). With power tubes removed - just 20mA.

I have disconnected all tubes, and run amp "empty", after some time transformer becomes slightly warm, but slight amount of smell was still present. I took infra-red digital thermometer with laser pointer, and noticed interesting thing. Transformer core was only 35C (95F), yet in one area close to the core temperature was 100C (212F)!

If there were shorts between different turns of winding, I assume transformer should draw a lot of power. However, it does not. Could it be arching between layers of winding, or whatever else?

Thanks in advance for any help.