I have this recurrent issue where I hear white noise through the Crack and I need to jiggle around the 12AU7 socket a bit for it to go away. The white noise does not fluctuate with the volume knob. Anyone know what might be causing this? I know it's not the tube since it happens irregardless of the tube I use and those tubes are quiet in other amps. I'm thinking it's a cold solder joint but wanted to hear any other thoughts before I try to resolder everything on that socket.