GE Roundie Issue

[Penthode]

Looks like it may be due to IF harmonic radiation. It looks like it is worst on peak whites which coincides with minimum carrier.

Try a different rf channel (channel 3 vs 4) and ensure the antenna connection is properly terminated and the 75 ohm coax to balanced 300 ohm balun is okay. It may help to move and rearrange the antenna lead to minimize this.

Also check all grounds around the IF and RF connections in the set and ensure the IF RCA connector to the tuner is tight.

I'd try this first before investigating further. Good luck finding the issue!