There are a couple things the first being that some of these trannys were made only for 110 volts, not 120 volts. And they were designed for 50 cycle current. (look at the numbers painted on your voltage selector)
And now you have plugged it into 120 volts, 60 cycle, and you have 50 extra volts of B+! That might not be good. And you will notice that it runs a might hot...
It is best to step down the input to 110 volts, really. If you want to get picky about it. My friend uses a variac to drop the voltage. But you also want to be sure that the tubes are getting 6 volts, at least, heater voltage, after the line voltage is dropped.
If the heater voltage drops below 6 volts the life of the tube is really shortened. Therefore "brown-sound" with the heater below 6 volts is not such a great thing either.
And then after that the amp should be re-biased, and it should run 20% cooler, or in that ballpark.
One other thing to check: make sure the 1K screen resistors are installed on pin four of each output tube. Some amps do not have this installed, and watch out.
Also of course your old leaky filter caps will make the tranny run hotter too.
