Date registered: Dec 2005
Vehicle: 222.132 & 221.122 & 212.025 & 906.633
Mentioned: 3 Post(s)
Quoted: 37 Post(s)
Kyle talks from experience. From reading the W211 forum the multifunction switch issue seems reasonably common too. Parts must be different though.
Some have suggested using compressed air or some cleaning stuff, that may give a temporary cure on the W211 where the switch is a signal switch but on a W203 too it would at most drive a relay.
Changing the switch is not that simple (I assume it is the same as on a W211), you would have to remove the steering wheel with the air bag, be careful with the wiring, clock spring etc. But you would probably find a guide from the car specific section.
Good luck for the task, at least your story was convincing, if you decide to do it yourself, I hope you get all the help you need.