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Well, I went poking about the video board to see if there was anything obviously wrong that might reduce the luminance frequency response. All the peaking coils measure the correct resistance. Shorting them or bypassing with a large cap generally makes things worse. The coil in series with the delay line is critical to matching the delay line impedance and preventing reflections that show up as a ghost image. Bypassing or shorting that one increases the high frequency response somewhat, but produces the reflections. Comparing to the CTC-7: the CTC-7 has some different RC values plus an added coil in the cathode circuit of the first video amp. I suspect this is added video peaking.
So, I think the video amp is performing pretty much as designed, which is to say, it could be much better if there was a way to flatten the response to 2.5 MHz or more.
By the way, the spare video output tubes I bought did not make a difference.
This morning, one of them decided to fail, although it had tested good - picture started getting brighter and brighter and control had less and less effect.
Only thing left to try is a full alignment, though I'm guessing it's not affecting the luminance response, since there seems to be plenty of chroma.
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