Okay I have an update:
Today I finally received my RF modulator. It has enough output to transmit a signal several feet. This absolutely, certainly, without a doubt, gives me the ability to rule out video source and cables.
It has been a long time since this Chromacolor II pulled in anything over the air...
Now lets see how the CTC 166 looks with the same signal:
Hm. That's actually not that bad. I can still see the smearing, but it's better.