Yesterday all of a sudden there was a very erratic screeching noise coming from the amp. I tried swapping the tubes to no effect. The volume control doesn't do anything to the noise. What could be the issue here? Thank you.
After moving the tube a bit I noticed that it stopped, but any slight adjustment makes the noises come back. Should I just reflow the solder at the socket just to make sure everything is fine?
You can also use needle nose pliers to slightly bend the 4 pin socket contacts closer together, though you didn't say which tube you had to bend to change the nature of the noise. It's also possible you have a solder joint that isn't 100%, and moving the tube around is disturbing that joint.