I'm not a tube old-timer, but I clean my tube pins with either Caig Pro gold, Flitz, or whatever appropriate product at hand. I then apply a thin layer of contact enhancer, in this case Sil-clear, fine silver paste to insure best contact. As elsewhere in electronics, clean, tight, connections are job one in trouble free use of audio equipment. Do use clean hands or gloves when handling your tubes, however.
Regards,
Dan
Regards,
Dan