Hi, I have a kirk quick release clamp and had bought an Arca Swiss Z1 sp ballhead with 1/4 inch screw. I fastened the clamp onto the ballhead by tightening with the screw. However , in portrait , there is some play when I use heavy camera like Pentax 67ii , as the clamp is resting on the felt mat on the ballhead. I would appreciate any suggestions. Thanks and have a nice one.