Recently I had to replace my tubes because It would get that familiar tube loud noise crackling and lose major power, someone said it sounded like Power tubes so I replaced all 4 EL84's with GrooveTubes, I believe they might be Sovteks, but not sure, that didn't fix the prob so I replaced the 3 12AX7's with mesa boogie ones cuz that's all GUITAR center in Tacoma had, it still would crackle i found Metal Spring loaded cover on the far right of the three 12AX7's would crackle and so I thought it was a bad new tube, plugged it in sounded great, left amp on standby for about one hour came back and started up with the same crap again, messed with the cover on that far right tube so took all covers off and seemed to work, left on standby after a little online research about the metal spring loaded covers, came back and same crap with the far right tube, I'm beginning to think that that particular tube socket is bad so I think I need to take it in somewhere here in Seattle/Tacoma to have a Pro do it and check it out. It's either that or those Mesa Boogie Tubes suck, but if that was true how come it seems to just be that tube socket?