That he said the sound was good made me think the B+ is okay, or at least ballpark.
It could still have horizontal oscillator problems keeping it from getting any high voltage, that's why I suggest checking that first. If it has HV and a dark screen then the Ion trap may be misadjusted, the CRT may be bad or it could have video problems.
The 9QP4 was a disaster, GE replaced a ton of them under warranty, the replacements may not have been much better. My own experience with these sets is not good as far as CRT's go, I've had to buy several junkers to get good tubes to fix my better sets.
There is some information on repairing these sets here:
http://antiqueradios.com/forums/view...hp?f=3&t=91582
And some info on the Tube here:
http://www.videokarma.org/archive/in...p/t-52670.html
They are so simple you can replace all the paper tube caps in an hour or so, a little more for the Electrolytics.
I've had to replace the Horizontal AFC Diodes on the ones I've done, they are Selenium and don't hold up.