Len,
I have also found another "Buzz" location on the ZE......Where the turnbuckle sleeve attaches to the cable slide on 2 different rests I've installed there is a small (maybe a 1 /32"

gap between the edge of the sleeve and the set screw.
On both occaisons a small stainless washer between the sleeve and the slide filled this gap perfectly and turned a noisy rest to almsot silent.
Check to make sure there is no "Play" in this connection.