Looks like the horiz control side may be soaking down the osc side because the triode cathode is at 28 volts. Look to see if R454 has shifted high and running the triode into cutoff. One thing I have done in the past at least with my Sylvania and a few others is sub in a 6GH8A for in my case 6BL8 and had good results. 6GH8 is a medium mu triode/sharp cutoff pentode and pins all line up internally with the 6JW8 that you are running now and the tubes are similar electrically but not exactly, this may only help you isolate if its a bad tube or other problem.
One thing is do you have a replacement for the 6KD6 by chance? Ive had dampers arc out in the past and the resulting current swings have also taken out my horiz out tubes. A 6JS6, 6LR6 would be good subs as they pin the same and have similar ratings within 10% of nominal voltages. The 6KD6 is a bit more robust than the 6JS6 however the JS6 will survive as I have used this tube in several sets that have called for a 6KD6 and 6LR6 such as my Sylvania.
Last thing to check is supply voltages themselves however they will be elevated with the horiz tube out of its socket but all the voltages should be present.

Im not an Admiral expert by any means but Ive burned my fingers a bit over time with glowing horiz tubes.

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