Carefully pry the trim off around the switch, remove the 10mm bolt, slide the assembly forward and it will come out.
Be careful do not lose the ball bearing when you open the switch. Lightly sand all contacts and spray some WD40 on them. You need some luck in order to snap the switch back in 1 try!!

Good luck!

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Peter Chu aka PIKACHU
08 C300 Premium Pkg, MM Pkg, Sport Pkg, Keyless Go
86 300E soon to be E36 with Euro Headlights
400E front & rear brake upgrade
16" CLK wheels with Michelin MXV4 plus Green X