Gerry O’Hara wrote:
Often the grid cap of a tube can become loose or detached due to aging of the glue that adhered the metal top cap to the glass tube envelope. The cap thus loosens and makes the wire connecting the cap to the tube grid vulnerable to damage (snapping) when removing the grid connection clip from the tube during servicing. This happened to me recently on a Type 75 tube in my Sparton chassis. Luckily there was sufficient of the grid wire remeining to allow me to solder on a new length of wire and re-make the connection to the top cap. Make sure that all the old glue is cleaned out of the top cap and use a small amount of epoxy glue to re-cement to the tube envelope. The photos below illustrate this simple fix.
Thanks Gerry! It is quite helpful I salvaged 4 tubes in my collection.