Libec LX7 M - Manual (Page 7)

If the camera tilts to the backward or forward, adjustment is
needed to shift the sliding plate front or behind.
The head may tilt while adjusting the sliding plate.
Keep hold of the camera to ensure it does not fall off.
Hold the camera and loosened the sliding plate lock.
Move the sliding plate front or back and find the position
where the tilt balancing can be obtained, secure and tighten
the sliding plate lock.
D: Adjusting of sliding plate