cleaning base pins

Use a pencil eraser to gently rub off the tarnish 

Hi,
for gold plated ones i use tarn x once and clean it afterwards with a cotton pad or with a fabric for plexi glass. For non plated ones emery cloth 1200 till pin colour is uniform and then with pure alcohol. Lettering on most vintage tubes is very sensitive and will go away with time and when cleaning dry the envelope.

If you just have too. LOL the best for no damage and a good PIN cleaning lowrider57 hit the nail on the head.

If you want to clean but not remove material and POLISH pins.  Get a small handful of cotton balls and put, Deoxit, Rislone, or gun oil, on the cotton. DON'T get crazy, just a bit, and plunge the pins several time into the cotton. They will polish right up. Wipe off the excess. I leave a thin film on the pins..

Some of the old valves have a powder type ID. BE CAREFUL it will rub off, no oil or alcohol on the writing, ok..

Regards

Often tube pins don't need cleaning, but if oxidized or dirty:

Isopropyl alcohol or Deoxit D5 (wipe off excess).