bad tube ?

[bgf]

i have a BeePre 300B Preamplifier for a couple of years with two bottlehead mono amps and a eros phono preamp.  last week the left channel started to have static come through the speakers (klipsch  cornwall).  i checked the speakers connections by switching right and left. and tubes on monoblocks right and left etc.  until the left  300b tube on the preamp reproduced the static in the right channel.  should i replace the tube and is this a common symptom??? thanks

 

[Doc B]

Try cleaning the pins first. It might just be a dirty contact.

 

[bgf]

thanks that did the trick, looks like i might as well spend some time this weekend cleaning the other pins.