[alistair kerr]

I have a 52 plate V70 2.4t auto with geartronic transmission. The plastic lever(inhibitor button?) on the gearknob that allows you go into the park position from drive suddenly dropped out of the gear knob. On investigation I found that one of the plastic parts that a pin goes through had broken.
Could some one tell me how to to get the knob off so that I can fit a new lever?
Many thanks
Alistair Kerr