I figured it out, but it was kind of a circuitous route. The fuse blowing was the result of the HOT shorting out. I unsoldered it and measured the emitter-collector resistance, and it was only about 45Ω, instead of infinite like it should be. I subbed in a new 2SD1555, replaced R808 with a 200Ω brown devil, and replaced the blown R417 with a new fuse and everything came back to life. The HOT must have blown from the exposure to high voltages while I was testing.
At this point I had a stable picture, but there were still a few problems. If I turned the brightness or contrast up, the picture would shrink and/or cut out whenever displaying a bright scene. I measured the output of Q802 and found it was only around 105V, HV was a little deficient at around 22kV. It also seemed like R808 was running hotter than it really should have been.
Now I look at the input of Q802, it's still a healthy 160V, so the rectifier and filters are good and nothing is being loaded down too much. I check pin 2 of Q802, the base drive, where the schematic calls for 125V and find 157V. That's weird, you would expect higher output voltage with a higher base voltage. I check the voltage at the voltage divider feeding the base of Q802, between R805 and R807 and also find a higher than expected voltage. The only thing I can think of is that the base is not connected here, so I test R806, the 47Ω resistor connecting the base of Q802 to R805/807 and find it open.
I replace R806 and everything is PERFECT. I'm getting exactly 125V B+, HV is about 25kV, and I can turn the screen, brightness, sub brightness, and contrast controls over their full range with no problems. My theory is that the original problem was failure of R806, which caused R808 to overheat and change value, which caused the high voltage that lead to the shutdown issue.
I'm attaching some screen shots, this is the first time in about 20 years this set has displayed any kind of a picture.
Thank you so much for your help, I always learn something new on every one of these projects and this has been no exception.
