It will be one of the rods sticking / unclipped.
Go to shop and buy pack of door card clips - they will break! Part Number MXC1800
Remove handle - 2 screws under flaps at end
Remove window winder = kinda clipped in from the back
Remove the surround for door handle on the inside - 1 screw.
Remove Door Card.
Prod about a bit till it works.
:)
This is what it looks like courtesy of google. One of the metal rods will not be working correctly - should be easy to see whats up.