[Arran]

I like to use Permatex windshield adhesive and sealer, it works good on grid caps, and to re attach a tube base, as for fixing a loose one I have not tried that yet without removing the base first. I often do this with the tubes with the old style bases since the solder joint on the pins are often bad as well, like on a #24As, #45, #47s, #26s. Without taking the base off I think that I would go the epoxy route.
 I learned about this substance from our own Bob Andersen, but unlike Bob I bought the black rather then the clear kind. By the way, I also used it to glue some new tube sockets in place so they wouldn't spin, they were the molded Bakelite type with a wavy clip ring, and are supposed to go in a keyed hole to stop them from rotating, which this Electrohome chassis did not have, the Permatex did the trick.
Regards
Arran