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.
How hot should my WAVAC 300b run
Just bought a used WAVAC 300b amp. Sounds great, but it is running VERY HOT. Without the tube cage on, the metalwork is very hot to the touch. I can hold my hands on it for 15 secs or more but just barely. I also smell a burnt wood smell. The wooden faceplate is warm Anyone with any experience on this? I will contact WAVAC but have no experience with how they treat purchasers of used units.