I thought I would share this as others who have a CRT with a similar problem and may benefit from giving it a try.
I had a 1950's 14" 90 degree Mullard CRT given to me FOC by a kind member of another forum. What type I do not have a clue as the sticker is gone but that another mystery to be solved later.
The main problem was the cathode lead-out wire had broken off right at the base, there was nothing poking up at all it was a flush break to the glass base.
As is often the case a plan was hatched in my sleep, yep dreams are great playgrounds for solutions (see pic 2). I contacted Trevor and ran the idea past him to see if it was madness to even attempt. Trevor thought it was worth a go nothing ventured nothing gained as such.
I placed the CRT in it's tightly packed small box and I wrapped a blanket around the whole thing just in case the worst happened.
As I said the wire had broken flush to the glass surface, so under the mag lamp I worked away all around where the wire tip could be seen with my Dremel. Using the finest engraver I removed glass creating a litle cup like an oil cup on a clock plate. Eventually a little bit of the wire became exposed. I cleaned the top of the wire so it would get a good bond.
I then applied RS conductive paint to the cup, theory being the exposed wire surface would bond and the cup would form the larger area conductive area.
When this had dried I found some thin wire, put a kink in one end so it would sit in the cup. I then taped the wire in place and coated the wire and the cup again in conductive paint. I then used felxible epoxy resin to cover the wire and cup to ensure a secure fix.
Once dried Success, the cathode lead out had made good contact and is conducting. My CRT tester could see the cathode. Bad news was the tube was low emission. All was not lost so I left the CRT connected and set the tester on the gentle ageing process to see what would happen. After a while the emission started to rise, eventually settling to 100% emission.
I'm one happy bunny a 1950's CRT saved from the tip. Now I just got to figure out what Mullard tube it is MWxx-xx and the put in the stores with the others.
Hope someone finds this of use, but I except no responsibilty when you go diging at the base should it go pop!