Did you return it? That balltop definitely defective
I had this issue once, I fixed it with a tap and die set.
I missed doing this simple test before making this whole post but I used a slim metal object and put it in my old balltop then hold where it stopped then put it in the new one and it clearly doesnt go all the way down so that Balltop must be for sticks that have a shorter rod to screw onto… returning it then having to pay to collect a new one would be too much just for the ball and it didn’t cost much so too much hassle to me
Maybe it’s on all the way but, the shaft sleeve you’re using is a bit short? Making it look like it’s not going down?
The shaft cover isn’t short if I use the old ball it touches it’s the clear ball that has less screwing distance I’ve tested n proven it