Might be barkhausen(I think I misspelled that) oscillation from the horizontal output tube.

that is not barkhausen, but its just prob something within the i.f or tuner, try tuning to channel 4 instead, and make sure all tube sheilds are seated and the twinlead to the tuner is dressed away from other things, what I did was add the 300-75 ohm transformer/adaptor right in place of where the twinlead used to go. so if I want to tune FM I just turn off the TV converter box and it still passes a signal for FM.
did you notice that hole cut out under that chassis which looks like it was for shipping the Yoke Assy? the bolt pattern aligns up on the wood support

It doesn't have twin lead it has a direct 75 ohm ( i think 72 ohm ) rca phono connector to a shielded cable to the tuner , i tried tunning and hen the image is tuned right that pattern really isn't noticeable , i do have to try to align the if adjustments , if you look close at the not so good picture after the last letters you can see the shadoes/ghosts of the letters , so i'll see if i can eliminate them , if not it plays well as it is.

so thats what that big round hole is for , i couldnt figure out what its purpose was

mike

If there is a shielded coax running from the tuner output to the IF strip, check to see if there might be a broken ground at one end of that cable.

I'm slowly but surely getting there.

mike