Yup. Used to get regular work from the arcades back in the day; principle is simple: overdrive the heater a little for a short period, apply a HF signal to the cathode while it is boiling from the overdrive, this strips a microscopic layer off and get you good emissivity again. It is as much art as science; getting all 3 guns within 10-20% without smoking one of them takes some practice.
Yes, it is a somewhat destructive process; but the CRT is already toast, so why not.
My experience was that specific units at the arcade would last 1-3 years after a zap; that's a machine that runs 12-14 hour days 6 days a week. I usually was able to zap a CRT at least twice before the gain was insufficient to balance the guns; then you know who they called to do the CRT replacement. Ka-chinnng! ![Wink ;)](https://www.eevblog.com/forum/Smileys/default/wink.gif)
mnem
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They had one at the TV Studio where I worked, & I often used it to get a bit of extra life from some of the less critical pix monitor CRTs.
For some reason, "delta gun" tubes didn't do as well with it as Trinitrons & the various other variants, like "Linytrons", etc.
We usually only got one rejuvenation out of each tube, as towards the end of life, there was usually one gun that just wouldn't come up.
BW tubes were much more forgiving, but, eventually they started showing massive gamma errors.
There was a very good local regunning facility.
It didn't look much, but the proprietor did an excellent job with Trinitrons, wth results indisinguishable from a new tube.
Again, the "delta gun"tubes were a lot harder to get right.
It was normally not our practice to use regunned tubes in critical monitors, but during a period of financial stress, we (unofficially) relaxed that rule, with good results.
I developed a lot of expertise on pix monitors which I neither desired or anticipated, being mainly employed as a Transmitter Tech!