polishing pins of NOS tubes

I’d try Deoxit first. I think a Dremel variable speed cordless with the small felt wheels would be good . Personally I’d anchor the tube in a safe manner on a flat surface and use both hands resting on the same surface to avoid a woops . I’m fairly experienced with accuracy rifles and avoid using stainless brushes on stainless or regular steel barrels. I use a high quality brass brush. We have different solvents to use mainly to remove copper buildup and we need to be careful not to etch the barrel. Those solvents usually have a strong ammonia smell. I’ve often used a fine paste valve lapping compound for various metal related tasks like lapping aluminum and steel scope rings. A polish like that might help.  I’m getting off track for your sake but just wanted to share a general overview of stuff as not to get too carried away. I hope my abstract speech helps in your search. Regards, Mike B. 

what about the sockets the tubes were in? corrosion? loose?

Just put a small amount of gunpowder in the tube sockets and blow the crap out of 'em. Put the tubes in the dishwasher to clean the pins or cover them in peanut butter and let bugs eat it off.

Yeah, great technique to clean those nasty tube sockets.

I clean connectors with British Kontak, it's a military grade brew. I have never tried cleaning tube pins yet, though.

scotch brite pads for the pins; these tiny little bottle brushes for the sockets