Zenith 18CC30 no longer regulating

[Davala]

The TV was a daily driver for about 6 months before it had a failure. I dozed off while it was on and woke to it having a dim and shrunken screen. No arcing or smoke. Flyback seems fine. A quick power off and on returned the brightness but I noticed as the brightness changed the pincushion on the lower right of the screen would bend and straighten.

I've replaced the trio of HOT/damper and the 6JH5 but it still seems to not regulate. HV is set to 25k but as I vary the brightness you can see the meter fluctuate and the screen size changes.

This pulse type regulation is not as simple as the shunt style and I dont know how it works. I'd like to understand why it's not regulating.
I'd like to check R177 off pin 3 of the 6jh5.
I'll probably shotgun replace C118.
Theres two diodes, x28 amd x26. connects to the cathode of the regulator. whats that for?

Anything else I should check or just replace?

Thanks,
Matt Davala