Thanks guys for all your help. Problem solved by lubing the wiper mechanism. To accomplish this fix on a mono-blade W202:

1. Snap off the plastic cover at the base of wiper arm;
2. Remove the bolt holding the wiper arm onto the mechanism;
3. Remove the wiper arm;
4. Remove the plastic cover over the wiper mechanism by carefully prying the sides of the cover at the bottom of the cover (closest to the engine) away from the sides of the wiper mechanism and lift it off;
5. Apply some grease with your fingers to the wiper shaft that moves the single wiper arm up and down;
6. Turn on the wipers to see if the mechanism works smoothly and to spread the grease around;
7. Reassemble.


This job takes about 20 minutes and should be done every 60,000 miles or so.

__________________
Marc
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