I've had the exact same problem. Now mine just all of a sudden started working again one day so I didnt have to do anything. To start with let the amp stay unplugged for 24 hrs and check both fuses. If they're good check the tubes by turning on the amp and see how illuminated they are. Possibly then check the tubes by pulling them out. You can then get new tubes or sit it down for 2 weeks and then come back to it and then it works fine and if it doesnt possibly get tubes or take it to a tech. How long have you had the amp and when was it re-tubed and biased.