51 22 004 Adjusting Rear Left Or Right Door Detent (Lock Wedges)
WARNING: This page is about a different car, the 2008 BMW Alpina and 2007 BMW Alpina. However, it is still accessible from the selected car via links, so may be relevant.
Operation is described in:
Adjusting left or right rear door . See 41 51 004 ADJUSTING LEFT OR RIGHT FRONT DOOR .