Ok. Ill look later when kids are in bed but if that's the problem how do you fix it?
There are two nuts inside the cabinet that retain the whole assembly - loosen those and you you have 'wiggle room'
The mushroomed tip is caused by NOT replacing the tips often enough and the plunger striking the ball, that's why I suggested stocking a few rubber tips - they are dirt cheap and prevent this problem you currently have - also prolongs the life of the balls.
