A Lemon set?

[Einar72]

I don't wanna go too far out on a limb having not seen the schematic, but there may not be enough performance engineered into the poor old thing to not have some buzz. I think it was Zenith that had a pot somewhere in their design called a "buzz control". The usual cause of buzz on white-intensive video (like text) is the strong white-level signal "spilling over" into the sound circuit. I wouldn't expect the poor little Muntz's AGC circuit to handle the overmodulated video signal from a modern VCR/DVD/Cable Box/NTSC Converter modulator, try an attenuator on the antenna input, since there's no more need to have weak-signal capability...