So a friend of mine had this amp. It was giving him trouble so he took it in to a local shop several times. Nothing was achieved. He has since bought better amps and really gave up on this one. He has given it to me to fix or scavenge. A free Bugera, hmm well worth a shot at getting it going. It runs ok for a little. Then the tube monitoring on the back shows a problem with the number 1 power tube. It gets quite and sometimes no sound at all. I took all the power tubes out and swapped positions but I still get the number 1 power tube led lighting up. Has anyone encountered this problem? Could a bad preamp cause the light to come on?