Personally, I'm surprised that you haven't repaired incandescent light
bulbs... or maybe you have?
I once found some info about people who repaired CRT
tubes...!!
Regunning (TV) CRTs was common in the UK about 40 years ago and there
were several companies who did it.I doubt, alas, any still exist
Many years ago there were multiple valves made by Loewe. These were
large-ish glass envelopes containing triodes _and the components to
interconnect them_. A radio receiver could be made using little more than
one of these devices, a tuned circuit, headphones and batteries. The
first integrated circuit if you like. Anyway, apparently there was an
official cervice to have the filaments in this device replaced if they
failed (the most common failure, of course).
-tony