Maybe there's hope for the old girl yet.
(Ignore the dark horizontal band, which is a camera artifact.)
Today I went on a resistor hunt, checking every resistor in the color signal path, starting at the point where the video signal is picked off from the IF section and working through everything but the demodulators.
I replaced a number of resistors that were out of spec. Then I powered up the set mainly to confirm that I hadn't made things worse. I also wanted to scope the outputs of the quadrature transformer to see if anything like a signal could make it out that way. After several scope photos and a few adjustments, I was surprised to see real color bars for the first time on this TV.
Yes, I know the colors in that pattern are incorrect. There's obviously a lot more work to do, but it's nice to see a little improvement. I'll finish the resistor hunt tomorrow or Saturday.
Phil Nelson