I hooked up a color bar DVD tonight, and it appears the video output is OK after all - I'm getting the peak-to-peak reading specified in SAMS, although it's lower than I guessed it would be. Also, the color circuits locked right in and are producing classic-looking waveforms on the G1's.
Also, the vertical hold seems to work OK.
I checked out the action of the contrast control, and I can see why there is a suggested change. There is quite a bit of quiescent current in the video output tube, which is changed by the DC coupled contrast control setting. This results in wide swings of black level (brightness) when the contrast is adjusted. The change to capacitive coupling will eliminate the DC shifts.
I have got to get the CRT mounted somehow now, because it looks like the chassis is fully functional.