Random crackling in left channel, getting worse

[fung.chan]

Hi All!

I have reflowed and/or redid the solder joints completely AGAIN and it still crackled. Defeated, I left it to play music at a low volume overnight. Lo and behold, this morning, for three hours now, no crackling at all! Over the moon at the moment.

However, an extremely high pitched squealing noise is now coming from the physical 6080 tube itself, which goes away when I tap it slightly, but keeps coming back. From everything I've read and suggested before this, it could be tube ?oscillation? and I either need to A/let it run for 50-100 hours, B/ Bad ground which I don't think it is or C/ A bad tube.

Doc: I've already reseated the tubes multiple times, the 6080 has next to no corrosion on the pins, unless it's something my untrained eye is missing. What method would you recommend to get rid of corrosion?

Thank you to everyone in advance for their incredible patience

[Doc B.]

Cut a Q-tip in half and chuck it up in a Dremel. Dip it in some metal polish like Simichrome, etc. and polish each tube pin.
If you don't have a Dremel just try buffing the pins by hand with a Scotchbrite pad. Then apply little Deoxit to finish. Use the Deoxit on the socket contacts too.