1: Remove the tailgate internal trim to access the tailgate release trigger plate and rear wiper assembly.
2: Remove the black cover (1). This is quite fiddly and cable connectors will need releasing, pay attention when removing as it is tricky to get back into position later. Also look out for the tailgate lamp connection as the cover may catch on it during removal/refitting.
3: The two socket head screws can now be released with an Allen key and the trigger plate assembly removed from the tailgate.
4: Remove the rubber weather boot and carefully unclip the micro-switch (2). If required, you can test the micro-switch operation by reconnecting it to the tailgate. Close the latch on the tailgate locking mechanism and depress the micro-switch at which point the latch should release.
5: If you have the same problem as I did, the trigger plate will will be tight and the micro-switch spring will not be able to release the micro-switch at (3).
6: Area (4) shows the area that was tight on mine. Use a dremel attachment or file to remove a little material from the casting in area (4) and the trigger plate should operate freely. Refit the micro-switch and test the the operation until the micro-switch spring can release after operation.
7: Refit in reverse order and test.
N.B The black cover (1) is difficult to get back into position, don't force it - it will go, make sure you don't snag the wiring when refitting it.