[PointyFox]

I'm using a Bruce Bender 6N1P OTL amp, and when the tubes move (such as by heating or bumping) they make a crackling noise in the output signal.  The new mini 9 pin tube sockets are ceramic and the tubes are also new.  All 3 tube sockets produce the noise, and it is only on the left channel.  I tried DeoxIT, which seemed to work temporarily, but they're still crackling.  I heard something about retensioning, but I have no idea how to do that and thought that this shouldn't be necessary with new sockets.  Any ideas?

 

[spritzer]

It could be a loose contact in the tube socket (these are often pretty cheap) so you can bent the metal contacts a bit closer together to give you better grip on the tube pins.  Another factor is that many tubes are simply noisy and microphonic and that noise can be transmitter though to the output.   I would also check the soldering to see if you have a cold joint somewhere,  

 

[PointyFox]

It's not microphonics, also, I can't access the socket contacts.