Two questions

What paint is best for the black trim on some radios?

Can or should you fix a loose top cap on a 6c6. The tube works ok

Re-solder the top cap. Then drizzle in a little super glue under the cap. Wait for it to harden. Then trimm away excess if you wish. If the tube gets really hot, super glue won't work too well. You might try JB Weld. Before doing anything, make sure that the hole where the wire goes through is clear, so that the wire may pass through easily. Place a little JB Weld under the cap. Fit it in place and solder the wire.

T.

:Two questions
:
:What paint is best for the black trim on some radios?
:
:
:Can or should you fix a loose top cap on a 6c6. The tube works ok
:

If you are going to overcoat with laquer - probably a decent quality black laquer will serve you best.

As for the grid caps - I've used super glue for years with no problems. Heat is most often not an issue as these tubes usually don't get as hot as rectifier or power tubes (where superglue can pose problems with envelope breakage if used to reglue the base).