While in very specific circumstances contact enhancers like Pro Gold, etc., will work wonders on older RCA connectors, some "aficionados" will extend the usage to tube pins. If you decide to use enhancers/cleaners do so at your own risk, and use the brush type (with extra moderation) an never the spray cans

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Whatever you do, please............never...I MEAN NEVER... USE ANY TYPE OF "HEAT TRANSFER/THERMAL COMPOUND PASTE" or the like

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You will create severe contamination to the tubes pins/tube sockets, and you will have expensive repairs not covered by the warranty!
OK, enough said...let's enjoy the music.
Regards,
Alex