Question on buzzing sound at low volume...

[Radiophile2001]

Hi, quick question for the AK braintrust:

On one of my tube sets, if the volume is turned all the way down or is set low, I can hear a buzzing sound. It can be worse with white lettering on the screen. If the video is off-tuned to distortion, but the audio signal is still tuned in (ie on a UHF station), the buzz goes away. It seems worse with more white on the screen, but not that much worse. Is this situation adjustable with the AGC control?

Thanks!