That's kind of bizarre. I'm actually confused trying to figure out how it would move up and down if its glued to the ball. The only thing I can think is that the 1/2" hole may not be deep enough and so the gray piece actually cant seat all the way down on the white nylon piece so the nylon piece has play in it, but again, if it's glued then im not sure how it would even be able to move. I know on my drill press, it hits the stop about 1/4" before I can reach the desired depth for the 1/2" hole, so I have to drop the bit down in the chuck a little bit to get to proper depth.

I will say, in my experience, the white nylon piece is so shiny and smooth it does not bond with the glue very well and it can separate clean from the glue, so I could see if there was some room for slop it could pop loose and have play like that. I sand all my white pieces with 120 grit sandpaper prior to installation and it seems to bond with the glue much much better. I had a few balls where the IT came clean out, all the glue was still in the ball, and the nylon piece came clean out. Since I started sanding, have had zero failures (knock on wood).