Apparently triode CRTs are about as testable as electrostatic CRTs. None of the CRT analyzers that I'm aware of can test them.
I wanted to know the health of the 10MP4 in the Sylvania. I decided to measure the emission by using G1.
At least now I know that the CRT isn't dead. I measured a very high emission, but doing it this way collects most all of the electrons emitted from the cathode rather than the ones that go through the grid. The portion of the cathode that they would originate from could still be weak. You can read about why here
http://www.sencore.com/uploads/files/RejuveCRTs.pdf
The Sylvania Technical Manual says that the G1 cutoff is measured by observing the extinction of the focused beam on the screen.
I plan on doing this. I'll need to supply the HV and also be very careful to start with G1 above the cutoff so as not to burn a hole in the screen. If it passes this test then it should be in pretty good shape.
Of course I could just test it in the chassis once I finish cleaning, recapping, and checking all of the resistors. But this is going to take a while and I'd like to know soon whether I need to get it rebuilt or not.
John