I've been using my MB Fusion pretty solidly for under a year now (into an MBE 115). I went to play the other day, and the tubes warm up, I get the distorted (but not like a blown speaker) sound of my bass for about a second, and then my sound fades away to nothing within a matter of seconds. I really don't want to have to send away to GK, but I think it is under warranty still so I might have to. This is my only head so I'm kinda s.o.l. either way here. Could this be an easy fix?