I finally took the lower end (Pan end) apart on one of my Libecs to see why it rocks when the lock is off.

The reason is that there are two concentric rings of about 15 mm depth that fit closely, one inside the other. One is part of the upper section of the head (the tilt , the other, the lower). There is a thin layer of silicon grease between the two rings. To retain the grease, there are several o-rings placed beween the rings.

On the outside of the ring attached to the the top section of the head, the lock shoe (kind of like a bicycle rim brake) presses on the ring.

When the brake is engaged, the outer ring is pressed against the o-ring separating the rings. When it is not, the gap between the rings is maintained by the o-ring. Since the o-ring is flexible, so is the joint and the top and bottom are free to move in relationship to each other.

The sad thing is that they could have cured this problem with the application of a single, relatively inexpensive roller bearing.

Guess I'll make a new Pan bearing for the head when I get some time.

There is also room to add an independent drag control to the Pan system.

Otherwise, this is a fairly nicely made head. It is just almost useless for quality Pans as built.