DeoxIT on tube pins

@stevecham  that's primarily why I asked - I too have fairly recently fitted NOS Telefunken tubes. I cleaned the slightly tarnished pins as good as I could (one tip I read was to use a very sharp craft nice & gently scrape the pins to expose a clean surface) wipe with a lint free cloth but not apply DeoxIT.

Personally, the mechanical movement of pulling out the "appliance" (plug, tube etc) will remove the oxidation at the the areas of contact and renew the new metals to each other. Of course there are other manual or chemical ways to clean the pins/sockets and also to "bind" the area of contact.

What is “wrong” with using pro gold, once you have cleaned the pins with their solvent?

I use DeoxIT D50L for tube pins. Here is the kit that I use and works great:https://www.musicdirect.com/tubes/caig-vacuum-tube-survival-kit

The general problem with using Caig Gold or any product(Stabilant-22) left on the pis... is the HEAT. The heat will gradually turn the stuff added to a hard, NON -CONDUCTING shield and reduce, rather than enhance the flow of electricity. Mainly due to using too much goo. Way too many folks think if a tiny amount is good, lots more is better... and thus the later crying that the sound has gone bad. Also the effect on the sockets is cumulative. So if you redo the pins a lot, the sooner the hidden socket sleeves will become messed up with the baked on goo. So in general, best to not use any at all.
IF (IMO anyway) one could resist the temptation to leave too much on.. I think it could be used But the amount would need to be microscopic at most. And done only ONCE in the life of the tube. (and for folks who do not tube roll only) So put the Caig Gold on. then wipe it off as well as you can with a cloth rubbing it off a lot. The tiny amount left is the right amount. and way less than one can leave on IC and power cord blades..