Mine was the same.
The solution was, when snapping it back together over tha ball joint,
to do it *lower".
When snapped together high on the joint, it would continue to wobble.
There as something about the position that made a difference in how it
is set for use.
btw, The two metal items are still out. They seem to be some sort of
glide rather than sprint or clip. But w/o a diagram I can't be
certain. Still, it works without them.