How hot should my WAVAC 300b run

I owned 3 md300b one had a problem and caused 1 side to run very hot maybe yours has a simlar problem contact wavac they are great folks and will help you.

I can hold my hands on it for 15 secs or more but just barely. I also smell a burnt wood smell

The wood smell (rather than electrical) is probably due to the heat shock the chassis gets as the amp is heating up.

If I were you, I'd take the amp to an experienced tech or very knowledgeable diyer friend to check the circuit. Just in case. (I'd also contact wavac, but you're already onto that.)

Sorry, I meant the Wavac MD 572 model, not 560.

I have two of the Wavacs, the 560 model and the 811B which use transmitting tubes, and the whole amp is very, very warm to the touch during operation. I would suspect the 300b model might run a little cooler because it is not the standard transmitting type tube used by many Wavacs, but for the transformers and chassis to be very warm to touch is not unusual. If you can hold your hand on the trannies or the chassis metal for a prolonged period, it is probably not too hot, but I have never smelled anything coming from mine that suggested burning.