...I CAN FIT A NEW ONE.? not sure if i have to replace the whole gearstick. i only want to replace the top part.

u might argos sell the top part of gear sticks
u might
it says works on most common models
so it should work

Now that illustrates the pinnacle of tat!
It will either unscrew or be fixed with a grub screw through the front of the knob.