Do you hear a raspy low frequency sound? Like a little motorboat motor in there? If so, the vertical is working and you no doubt have at least functional horizontal.
Don't overlook the obvious - the brightness might be down on the TV
You can't, unless you can easily (safely!) see up into the HV rect, see it glow normally. BTW, if you get an HV *pop* when you discharge the CRT, you no doubt have HV, which is going to be on the order of 12,000 - 16,000 or so. If you've got a hissing - like a gas leak - coming from the HV box, you have HV, and a good amount. Shut the set, discharge it well, and CLEAN THE HV BOX. Dirt might cause leakage, arcs, flashovers, and scary things that can be bad for the set.
Don't ever measure the horizontal output tube's plate - there's a big pulse riding on it.
BTW, sounds like you're gonna need an oscilloscope - get one that can go over 10mhz. They're cheap and a great investment.