Unstable Zone Markers
If you have a long video lead between the camera and the VT unit, the video will be stable but the zone markers might be unstable. To get better frame sync signals you can change the video filter circuit:
VT Module in Rack System - short out, with a link wire, R21.
Boxed VT or LVT Unit - short out, with a link wire, R38.
R38 is located between the
R37 and C39 labels which are
visible on the board.