Last night I was playing on channel two as usual. After a while I decided to add a little fuzz to the sound. At first the fuzz didn't work, then it came on but the control was a little touchy. Only used it for a very short time and then turned it off. Played a little more and then set guitar down. Minutes later heard a loud pop and then the channel went dead. Channel one is still functioning okay. Where do I need to look and what do you think the problem is?