Audio "buzz" on a 1948 Motorola VK-101

[Resonance1]

Wow - that's all really great information and suggestions! Thanks to everyone.

I'll try slightly tweaking the three audio adjustments that can be accessed from the top of the chassis. Unfortunately, the most critical adjustment that sets the carrier to zero volts can only be accessed from underneath. I did do an alignment on both the audio and video before putting it all back together. I don't know why I didn't notice the buzz before, but I think that most of the time I was working on bigger problems. Since I've already aligned the audio once, and since most of you said that intermodulation buzz can be almost impossible to eliminate, I don't think it's worth pulling the set back out of the cabinet and putting it back on its side.

By the way, yes adjusting the fine tune does help. I can find a spot where the buzz is minimized, but not fully eliminated. It becomes imperceptible when the picture is mostly dark, and noticeable when the picture is bright - which fits exactly with everything you all said.