Yes, I've seen that happen. The trouble seems to me to arise because the whole lot is just held in by a shear force on that circlip. It seems secure enough when you first fit it, but the circlip can vibrate out after a while. Fortunately, the thing remains steerable, it's just very loose. These days when putting them in I go round the circlip with a suitable drift and give it a few taps with a hammer to help ensure it's well seated in its groove. I do this while I've still got the internals of the ball joint assembly supported - usually with a socket on a bottle jack, so it's not being pushed down by the force of the spring. So far, after doing this I've not had one fall out. Not yet anyway.
