GE13PF6504 no picture but green splotches

[technoman9]

Greetings fellow CRT lovers,

Ten years ago, I was using a 13" GE TV model 13PF6504 made in 1985 as my bedroom TV. One night while I had it on, I heard a "blip" inside the TV and suddenly the picture went all black with a few green splotches. The audio went quiet except for a 60 Hz hum. I promptly shelved the TV until I could find time to look at it.

That day has finally arrived. Last night I pulled it out and turned it on to confirm the issue. Strange thing was, as the tube was warming up I could see normal no-channel TV static on the screen, but as soon as the raster finished filling up the screen it went right back to displaying the black screen with two green splotches on it (see attached image below). The audio also is still quiet except for a soft but noticeable 60 Hz hum.

So far I checked the large power capacitor and found it's not shorted or open. I did see, with my Flir camera, the Degaussing thermistor hitting 200 F in just a few seconds so I shut it down and have not fired it up since. I checked the horizontal output transistor D1453 and found complete continuity (just one ohm) between the base and emitter, but I need to pull it out to see if that's the circuit doing that or not.

I've worked on stereos and cassettes decks before but never a CRT TV, so am appealing to you all in the interest of learning how to troubleshoot this. Any ideas on how I should proceed? Are there known issues with these GE TV sets I should be aware of? Should a Degaussing coil thermistor be reaching 200 F or higher in short order?