A small step and a lubrication bore later the foot opens and closes normally.
I still do not know what material is the clamp height adjustment. In the picture we say metal. But the touch that is similar to a plastic certainly good but I wonder about the behavior in time.
The bike clamp is superb, settings and screw connections quick and easy.
I put only 3 stars, due to poor machining of the feet that made it difficult to mount and broke a fragile paint (surprising, coming from Park Tool) !.
