For the 2 metal screws I suggest going to a good hardware store and buying the proper fitting lock washers - the ones with many "gripping burrs" buy the one that fits the best with either the inside or outside burrs. for the top of your plate above the knob I would put a thin gripping pad of rubber like is on most tripod plates. Should solve you movement problem.
juicesqueezer wrote:
On the third photo, if I remove the allen head bolt, can I install another manufactures plate on the ball?
I was also looking for an L bracket to attach to my d5100, since no matter how much I tighten the screw or the round knob, if I try hard, can move the camera. An L bracket would stop this problem for sure. Thoughts???