I have a Beltron, and its instructions tell you to select which gun to rejuv (so you don't do it to a gun that is good). The red-green-blue selector switch. So maybe you can return to the set and do the red and green guns, but don't do the blue gun.

Thanks RCA2000

I've tried to select the gun when doing a cleaning and I had it set to blue gun, the green gun lit up for cleaning.. As far as the restore function.. I haven't gone that far, so I don't know if that's different or not.. I haven't read that part yet..

Crack the end of that tube open and spray some Gumout on the cathode G1 area
then get on it on the highway and burn out all those old Waltons electron carbons
and put on a few good heavy metal videos and that tube 'll be fine.....

How about some good stiff acid rock for that tube? By the way Squirrel, try stealing seeds from a bird feeder when the pole it's on is coated in Vaseline.

This may not apply very well to our antique TV sets that are only occasionally used, but I have indeed rejuvenated CRTs that then lasted a number of years in some cases. Years of 24-hour-per-day operation, in fact. And, that may be the "catch". The CRTs I am referring to are in airport arrival/departure-type monitors that are never shut off (except for repairs). The "catch" is that in many cases when these monitors are shut off and later turned on again, they can take ten minutes to reach full brightness afterward. But after that ten minutes, the CRT looks very good while it had been poor before the rejuvenation. A ten-minute warm-up is not reasonable for a home-use CRT, however.

A family member of mine wanted to keep squirrels out of his bird feeder and of
course did all of the usual including vaseline on the pole..... Actually, all you
need to do is use a 4" or larger diameter PVC pipe so they can't wrap themselves around
it to grab it. I have always fed all out outside critters on the ground under a pine
out front, Squirrels, ground hogs, chippies, and all our birds share all the food
and get along quite well..... They have even adjusted to seeing our cats leer at them
through the window each morning...... In the evening Skunks, especailly baby skunks are
by far some of the most entertaining to watch.....

Back on topic, I have seen a number of people here post about what actually ends
the emissions on a tube, and brings about the end of life. In some cases I have read
that it's the getter material that "runs out" But the rejuvinating process only
effects the cathode really. I imagine items like "clean" button have some "truth" in
the naming of their function.... Does the machine heat and spark off some of the
cathode coating to uncover some unused material....? Could this be the reason in
some cases a rejuvinated tube lasts a long time....? And why Sony tubes generally
don't rejuvinate...? Is the coating too solid...? too hard...? Any theories....?

.

You need to have sufficient cathode material to work with. As the cathode wears, it becomes contaminated with the "used up" material. That's why depending on the thickness or amount of contamination can determine if you are successful or not.

A clean function is usually the mildest and will remove the least amount of material.

Unfortunately, there's no way of knowing beforehand and why some may shy away from the possibly of destroying an otherwise watchable tube.