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That is the craziest schematic I think I have even seen. Muntz would have been proud of this baby, full of European tubes and left over B&W tubes. I think The last time I saw parallel HOTs and dampers was in some late 40s B&W sets when they were trying to drive a 14" tube with a 10" chassis.
It's obvious why they changed the brightness control circuitry. In the first runs, they probably had considerable interaction between the contrast and the brightness controls. The version you have should have virtually no interaction as the contrast control no longer affects the DC bias on the cathode of the video output stage.
I was trying to figure out how the HV was regulated. It looks like they have a feedback circuitry going to the HOT grid circuit so when the HV goes down, the HOT grid voltage is changed so that the HOT stage is driven harder. I also noted two focus circuits. One has a separate rectifier and looks fairly conventional. The other one is just a big voltage divider chain with the HV rectifier.
I can't wait to see how this one turns out.
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