Relieve load on automatic slack adjuster. - AR42.20-P-0520-02A
WARNING: This page is about a different car, the 2009 Mercedes-Benz E350 and 2008 Mercedes-Benz E350. However, it is still accessible from the selected car via links, so may be relevant.
Lift center holddown clip (arrow) using a screwdriver so that the cable slack adjuster sets itself automatically.