Frankly, I'm not sure. I've replaced almost everything else I can think of. I have a seperate thread for that.
I recently replaced the Q551 part, and was getting some intermittent screen/neck glow, but eventually R809 popped again. I've replaced quite a few parts in and around there with pretty no change in behavior (until I replaced that diode.)
The original problem was R809 burnt up, and no neck glow. Everything else I've done replacing parts, nothing has had any impact until I replaced Q551, and then the screen was intermittent, neck glow was intermittent (sometimes fading and not coming back until I powered the system back up), until R809 popped again like I mentioned.
Replacing the flyback is really a last ditch effort on my part... I can't figure out what else could be wrong on this, and troubleshooting information is very difficult to find, and finding someone to repair it also seems difficult, and opinions seem to lean towards just replacing it with something else.