Selector's ball problem

Good morning, the first thing to introduce myself, my name is Yassin and I have a 306 sedan 1600 gasoline. The problem I have is that the other day I 3 Ys eme I stayed that march and the change lever is released, I saw where the problem was, I put the wave of the selector in the rods of the change lever and press it as I could, but every two for three I loosen up and I do not know how to grind it, forgive for my vocabulary.

Graciias!

Ok unfortunately you have no choice but to change the articulated union since these are teflon and surely that is very worn in any case that spare is common and should not be very expensive