What he said.
All my usual suspects are there, but then there are others.
With a scope, look at the H driver collector. Years ago I wrote a comprehensive post about how to read this waveform. Maybe it can be found, it was by snipped-for-privacy@aol.com and I'm not sure, it may be in the FAQ.
Between the collector and the B+ to the transformer there is usually a resistor and small capacitor in series. See the waveform at their junction, it should not match the waveform at either other end, if it does one of those components are open.
The most likely cause of a hot HOT is slow turnoff. Insufficient drive voltage can cause this, and yes I said voltage. It needs to go negative at the base of the HOT to assure a speedy turnoff. This results in such small abberations in the raster that they might be missed. Without a scope, you might see a compression at the left side of the screen, but you may have to reduce the width to see it.
Another cause for a hot HOT is that it is not turned on hard enough during trace time. If severe enough this results in a foldover towards the center of the screen. If so turn it off quickly, but you didn't mention that. Put a good crosshatch on it and look for any horizontal compression in the middle quadrant of the screen. (a middle quadrant if you will).
If either of these things happen it's the drive, but then. . . .
Any nonlinearity on the right side could concievably be due to slow turnoff, but in most sets it would be blanked. You would have to turn the contrast way down and turn up the G2 to see it.
There are plenty of possibilities on the HOT collector side as well. Cap or diodes that only decide to be leaky at a certain voltage, substandard replacement HOTs, yes, even if you get them from Sony.Interwinding keakage in any transformer involved in H sweep, or a partially pulverized core in same.
I would suggest you examine the geometry very carefully for any minor abberations in H linearity. If any abberation exists in a curve shaped area of the screen, suspect components near the pin ckt.
Last but not least (this from a Sony rep), run the set with the CRT anode disconnected. Some of the CRTs develop internal leakage which allows them to operate, but has a constant drain on the ultor voltage.
If the last scenario is indeed the case, it will run cool as a cucumber with the anode disconnected. Do not attempt to do this by disconnecting the CRT socket on a Sony. Take the red wire off.
If too many of these sets are around, it is worth figuring out a mod for it. It seems the HOTs are the problem, not the flyback. Look at the itsy bitsy flybacks new Sonys use. Or RCA, with TWO expensive FETs running it !
If a good enough transistor is the answer, it would be a simple matter to put one in and modify the drive. FETs are way easier, but then, alot of sets that use them have a lower B+, I'll have to look at their ratings.
Of course then they might start frying the choppers in the SMPS.
You know, logic dictaces that this might be related to temperature. Semiconductors are failing. Age of the semiconductor is not a factor because it is new.
If the few tubes Sony builds stay good, they night stay good for a long time. Of course there is this ineffciency to deal with.
Perhaps fans will do the trick. Those are steel heatsinks with no fins also. Am I on to something here ?
What say you ?
JURB