[drh4683]

One thing to note, switching from channel to channel on color programs could be totally different as far as tint goes. Transmitters then didnt have as good of toloerance for keeping the color difference signals in the proper phase like they do now.
An example, the zenith space command 600 has the feature to adjust hue. At that time, the hue control was a very muched used knob on the TV. This justified the development of the space command 600 with its hue control capability. Today, one who sees a SC600 thinks why even have hue adjust on the controller? TV transmitters today have such better circuits for error correction making a hue adjustment a one time adjustment on the TV.
The space command 600 remote lasted from 1965-1972. in 1973 The Space command 600ZX was introduced as the replacement and it did not have the hue adjusting capability. TV transmitters improved to the point (around 1973) that the critical hue adjustment from channel to channel was no longer an issue like it once was.