[Hallicrafters] Power transformer temperatures

[Waldo Magnuson]

Does anyone know what the normal range of temperatures is for power 
transformers?  I've been monitoring the temperature on an audio 
amplifier (a Craftsmen RC-2 which drives a pair of 6V6s).  I measure 
the temp at the mid-point on top of the power transformer with my 
wife's digital food probe and it has been reading up to 120.0 deg. F 
after a couple of hours.  Is this normal, or hot, or cool, or ?  Is 
there any guess on how much the cover on my SX-42 power transformer 
increases its temperature.  I've heard that over time the temperature 
tends to weaken the insulation amoung the transformer windings much in 
the same way as it dries out capacitors.  Any thoughts?  Thanks.
Skip Magnuson