I've been running my Stereomour II for years now and loving it.
One problem I've had is that the left 2A3 tube is very loose in the socket, and sometimes I get hum from it that requires nudging it slightly. I've re-flowed the solder on the sockets but that hasn't improved the problem. I've swopped the tubes. No improvement. The right tube is also not sitting snugly, but it doesn't seem to have this issue.
For now I'm happy to nudge it every now and then. Do I maybe need to replace the socket itself, or should I re-flow and maybe apply more solder to the joints again?
