Hmm, results inconclusive. I pulled the 3rd video IF tube and injected video from my little Leader pattern generator at the grid of the 1st video amp. The picture had extremely weak sync and it showed a faint image.
Then I looked at the CTC-4 schematic and noticed that the 1st video amp is expecting +2.7V on its grid. That pattern generator certainly doesn't provide a signal that strong.
I tried using my B&K TV analyst as the video source. Cranking its video output control to the max gave me something over 2V, but still not enough sync for a stable picture. Still no true color, either, but if the signal is too weak to pass a usable color burst, I'm not sure what that proves.
Phil Nelson