Hi guys, I´ve had this amp, which I love for 2 years now. It has fairly new tubes by the way (maybe 6 months old) Yesterday I was about to use it but there was no sound. Power light was on but the tubes were not glowing. So I put it face down and removed the backpanel just to see if I could figure out something. In that position I turned it on and the tubes started to glow. I thought that maybe there was a loose tube so I pulled all of them out, sprayed the connectors with some contact cleaner and placed them back in. It was working fine. Today the same thing happened and I tried banging the pack panel and when I did next to the power socket, the tubes started to glow again and the amp worked fine. So I think that something might be loose but I don´t know what that might be. So what would you think it might be? It does not appear to be something serious but I need to repair it soon, as I obviously cannot gig with it like that.