WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
I don't use superglue anymore because it easily breaks while inserting the tube in the socket. A little bit of elasticity is needed. It is best to avoid excessive glue, the glass evacuation stem should remain detached from the socket.