Tube Amp issue - fixable?

Have had a G&W T-2.6F for quite some time (acquired from a fellow HF member).

It's developed an issue where it will sometimes start getting a slight 'scratchy' sound while playing.  Very intermittent problem, but it keeps recurring, so I'm wondering if this is fixable, or just better to start looking for another tube amp....

The 'scratchy' sound is much (if not exactly) like when you pull or move one of the audio cables (line input for example), it could also be called popping and/or crackling.  I can also make the sound happen by gently 'moving' the tubes in their sockets.  It can always be 'cured' temporarily by moving 'gently' either the right or left tube in it's socket, but eventually it happens again.  Sometimes later that day, or sometimes the next day or whenever.

I do have several tube sets for the amp, and it happens with all of them.

For some reason my brain is thinking it's some kind of 'static buildup' (even though it's just sitting still) around the tubes and/or socket area.  Total wild guess, but that's what it's making me think of while trying to explain the issue.....

Any ideas of where to start?  I'm not opposed to opening this up and looking around, have all the necessary tools.

Thanks for any ideas!

Thanks for the replies!

'Rustling'....a new audio/description/related term for me today.  

I will tear it open and poke/look around for cold solder joints (days of college coming back to me).  Marginal resistor....I was slightly thinking it might be a component level issue, don't know if I want to go hunting for that.

Um....before I crack this thing open, how long after I turn it off should I wait before opening it up?  Don't have a circuit diagram, can't find one on the 'net....

Quote:

Originally Posted by samsquanch 

I'm not a tube person, so I could be way off, if I am someone correct me, but...

 

If wiggling the tubes is curing the problem (however temporary it may be), your contacts in your tube sockets could be dirty/corroded.  Hitting the contacts in the socket, and pins on the tubes with Deoxit could help.

Hmm....you might be onto something, along with adamus' suggestion on new tubes.....that is, before I open this thing up to check on cold solder/broken solder joints.

I just spent almost 30 minutes of inserting/removing all the tube sets I have several times (have 4 pair of various manufacture).  The insertions/removals (power OFF!) were a bit 'energetic/aggressive' (as if to positively make sure the contacting pieces were wiped clean both on the tubes and the tube sockets).  I can now touch and slightly wiggle any of the tubes (except one pair of Philips 6922s) and there is no 'rustling'. 

By the way....found a pic of the amp in question.