Grid Cap Repair

It was solved on an outside forum.

Look for stranded Teflon wire. It will Handle the heat and voltage. 
I was not aware of the style, before I wrote this so this applies to those that don't have the bakelight holder.

Remove the cap sleeve from the tube slowly so the tube cap has to release its grip otherwise the cement may break its bond on the top of the tube.

You could try a small bladed screwdriver to help break its grip, try not to twist the top sleeve cap as you don't want to break the wire under the tube cap but do not let it touch the glass.
Once you have it off , then desolder the cap sleeve wire removing all solder.
Solder new wire of appropriate length.  Replacing, of course the old brittle wire entirely.