Buzz can be a PIA on tube type Zeniths.
Try turning down the AGC control. Its along the back like the buzz control.
If its too high the set will buzz, too low & the pix will wash out.
Next problem is sources. These sets are before any add ons like games,
VCR, DVD, cable boxes etc so often they buzz or get torn up pictures.
Best test is usually a VCR direct to ch 3. The pix will tear at the top
but the buzz will be much less if at all if the TV is normal.
73 Zeno
LFOD !