Bad Tube In My '66 Admiral ?

[marty59]

Follow Zenithfan1's approach as he lists, and if the socket proves to be the source there may be one other thing to do. If the socket is in good condition you could try to retension the contacts. Caution!! Skill and patience are important here! Using a small precision scribe tip, you can pry the contacts against each other to reduce the circumference of the pin hole. If the socket is brittle, this will only bust it up as you are prying the contact away from the socket body. Sometimes the metal itself becomes brittle too and if that's the case the socket was not too good to begin with.
Octal sockets are easier to deal with also and in some cases the pins can be removed if necessary, and wafer style sockets with exposed contacts can respond to tightening with the gentle work of the needle nose pliers.
Sometimes you can save a socket over replacing it but like I mentioned you have to be careful!