The amp in discussion is a Mission amps Tweed Deluxe kit that I built. It has slightly bigger transformers and beefed up bias supply so it can take 6L6's with with a 5U4. I am running 6V6's with the 5U4 currently. Problem: When I am in full play mode the amp will just fade out to no sound all of a sudden as if I flipped the standby on but the light is still lit and in play mode. The quick fix is to shake the amp and hit it on the side a bit and then the sound starts to slowly fade back up to full volume. It will stay off quite a while until mess with it. Its sounds perfectly normal when running but just fades out arbitrarily. When it comes back on it will sometimes stay on for a hours. It all started last night after a 4 hour rehearsal. I messed with it all day today trying various things. Maybe getting to hot? I dont get it. Odd! Anyone have any bright ideas?