My box did not work well because the Bowden cable was bent - in order to replace it you need to open up the box. Replace it only with the correct Mercedes part.
Here are pictures of what the box looks like on the inside. The cable feeds through the grommet and hooks into the flap mechanism. The yellow part shown needs an additional "snap lid" (not clearly shown) to hold the cable firmly.
Most likely the foam layers are also crumbling. Replace with new 4-5mm thick material. Foam sheets are available from McMaster-Carr [http://www.mcmaster.com/].
The box is stapled together and can be taken apart easily - putting it together again is a different story. Get a good stapler - best would be an air-driven one - and a heat gun. You need to heat up the plastic otherwise the plastic will crack when you staple it together again.
Yup, another new adventure!
Good luck!
