[Angaria]

All of a sudden one channel on my ef5 (hifiman) hybrid tube amp got weak and then began to cut out.  Thought I might be the tube, but two other tubes showed exactly the same issue.  Swapping rca inputs and it remained on the same side.  If I wiggle the tube I can get a few seconds of play on that channel, but it doesn't last.  
 
What should I look for when I pull the amp apart?  Thanks.

 

[Solude]

Wiggling returns audio would make me think a contact point has come off.  The pressure from the wiggle restores the contact temporarily.