Hi, this is my very first post and unfortunately its because I am having a problem with my Mark IV. I bought a 2006 or 2007 wide body combo on ebay and just got it yesterday. Amp appeared to be in mint condition. Last night I plugged directly in, put it in standby for a few minutes and powered on. First thing I noticed was it was noisy on all channels. Wasn't sure if it was normal since I have never played one. Messed with the clean channel for a few then went to the lead channel. Used some of the settings on the Mark IV settings page here and really like what I was hearing. I then went through the entire manual to get a feel for the controls and I was happy. The distortion I got from the lead channel was just amazing. Didn't play much after that...kids. Anyways powered it on today and setup my clean channel. I did notice that the noise I heard yesterday wasn't really there. Then went to the lead channel and set it to one of the settings I had the night before. Well the gain was gone. It sounded slightly overdriven but thats all. I could get more gain from the Rhy 2 channel. Tried swapping preamp tubes with the spare and no change. Swapped outer and inner power tubes (Class A mode) no change. Tried all power amp options on full and tweed power, no change. Disconnected the internal speaker and connected to my 2x12 cab, no change. Not sure where to go from here. There is no smoke or burning smell. In class A mode the power tube in socket A is very blue and the others are not. In simul-class mode power tubes in A and B are blue and the other two are not. Not sure if that means anyting. I tried calling Mesa earlier today for technical support and they were closed. I don't know what to do. Seller says it worked fine.