Why does unplugging/replugging TT leads from tube phono pre-amp reset dead channel?

Hi All...
Lewm -- the male end of the Linn RCA is split, so I gently expanded it...that was a while ago in response to advice from a dealer a few months back.  It has not helped.  Length, though, I cannot change.  I have considered upgrading the cable on the TT.  It might resolve issue. I cannot believe the adaptors also have the issue with the Linn cable.  But who knows.  Thanks.

Al -- I will try that test next time the issue presents.  Thanks.  As to opening the phono stage...that will be done over the weekend...as it has 14 zillion screws and is a major hassle to open.  

Uber -- BAT had the unit in for an upgrade (superpak) and new tubes...the issue existed prior, I believe, and they could not replicate it. (Which is why they say its my TT, not their unit. However, I have another phono preamp...and never had this issue with that unit.)  I don't have access to another TT...but that is worth pursuing.  Especially if I can get it to happen with a different TT!  Thanks for the suggestion.

A mystery.

Joe

You really don't need to upgrade the cable so much as you need to try a different pair of male RCA plugs at the ends of the cables coming from your Linn. If you have soldering skills, you can buy any pair of aftermarket male RCAs and do it yourself.  I recommend Cardas, for ease of use or WBT. (I am guessing that you have one continuous set of wires from the cartridge all the way to the phono stage, so it would be a big job to change out the wires.  If you are using a traditional pair of ICs with RCA connections at each end, then of course you need to attend to the connectors at the turntable end, as well. Or maybe the wires terminate in a DIN plug at the tonearm end.  DIN plugs can be maddening too.)

Or by the way, have you ever unscrewed the protective barrels of the male RCAs at the ends of the ICs, to see whether there is an intermittent or cold solder joint to the hot pin?

Good news?   I have not been able to replicate the issue of late.  Perhaps this post will remedy that. I've ordered from Amazon a tube of DeOxit. Just in cast that's the culprit.  Next steps are to check loading on cartridge.  Suggestions on loading to address this issue? It sounds fine as it's currently set.  Also...will be interested in seeing what else I discover with the hood open. 
Lewm- The male RCAs from Linn simply screw open- very easy. How do I know by visual inspection if there is "an intermittent or cold solder joint to the hot pin."  I'm not sure what that means. Thanks. 
Thanks all.  

As expected...it couldn't last.  So the left channel dropped after a loud passage on Chet Baker's Chet. Great morning tunes.  I spun the plug.  Wiggled it.  Wiggled near the TT. Nothing. Pulled and replaced.  Channel returned.  I visually inspected the insides of the plugs...the solders look solid.  A bit of oxidation inside the ground part (inside the outer part).  
Thanks for sticking with me on this. 

Joe