Advice required on various issues please

OK Peeps in another twist my brain has been working overtime on what didn't fit right with the gear shift problem I've got.

I assumed because the prong was broken that is what was causing my gear shift problems, but today I can only get 1st(if I go for reverse) or 3rd and 4th.  Basically when I put it into the top half of the box gear I get 3rd, bottom of the box I get 4th.  In either gear I can move the gear stick wherever I like left or right and I can feel a rubbing through the gearstick.  I assumed this was the selector cable catch/end moving along the cable as it isn't gripping it properly, however now I am wondering why I can feel the rubbing.  Could this be something buggered at the bottom of the gear stick instead?

Cheers

Lennie