Tube Bias Adjustment and Tube Testing

All the octal pin based tubes I could think of use some sort of plating.Cleaning them with something real abrasive might easily remove the plating.If you could see actual corrosion on them,maybe use the finest steel wool gently at the most. Some may prefer Deoxit,or something similar.Don't leave a heavy film of Deoxit either.The miniatures like 12AX7's/6922's etc.,sometimes are gold plated.I think the same mellow process would work here.

I quit using DeoxIt a long time ago because of the film it leaves behind. I prefer a good cleaner with no film such as cleaners available at the Shack.

a good alternative to using emery cloth for contact cleaning is crocus cloth, which actually serves more of a polishing function. Sorry for going off-topic, but since we're already there...
Abrasiveness factor of crocus cloth is extremely light if any at all. Rub crocus cloth across your finger tip and it is very smooth compared to emery cloth, with which you can actually feel layers of skin being scraped away.
I use crocus cloth to polish away any oxidation surfaces from cables, fuses, switch contacts, relays, connectors, tube pins, phono cartrige pins, etc. It will not remove metal plating surfaces, just polish shiny bright.