Dont mess with it. It is part of the SRS system (airbags) and you could get real hurt trying to repair it.
Replace the assembly.
However. it could be bound up behind the b pillar.
To remove the pillar, Move the seat all the way foward.
Remove screws from plastic panel at base of pillar.
Remove front and rear door sill plates (pull straight up).
Remove door frame seals (the fabric covered ones).
You will see four metal clips on the plastic panel and four more on the pillar. Detach them from the door frames.
It is now able to lift out.
Be sure to line up the seat belt height adjuster when reinstalling.
Mercedes Benz Master Tech
ASE Master Technician
Owner of "Behind the Star Inc."