For those of you with later model Mercedes with the articulating arm, I've
been seeing a number of failures recently.

The grease in the head of the wiper gets hard, and the plastic teeth that
move the arm in and out get chewed up.

Result is the wiper jamming, or jumping time so the arm does not extend at
the 45 degree point.

What is happening is that the teeth that are fixed to the head get sheared,
which allow for the jumping or jamming.

Mercedes does not service just the plastic teeth, preferring to have the
owner buy a new assembly. Priced one lately? Would probably total an early
W124 or W201!

Subject car is a 1992 500SL, but it is typical for the W124, W201, W140, and
probably others....

Upon disassembly, maybe 40% of the teeth had been sheared off. Wiper was
jamming when turned on, would work for a swipe or two, then jam.

We removed the plastic teeth (2 sets) from the head, and cut off the
remaining teeth. Need to keep the top portion, since that is a labyrinth
seal for the head. Explaining further, the the system works like a rack and
pinion. The rack is attached to the wiper head and the pinion is attached
to the wiper arm. The rack is what is removed...

The arm is set to the retracted position, which appears to be a null
postion. Pulling on the arm does not extend it.

Reassembly, without the teeth, and arm in the retracted position resulted in
a wiper that worked fine without the articulation.

So far, we have not had any problems with it, and if the arm eventually
starts to extend, there are ways to lock the arm in the min position.....

Not my first choice of repair, but for a seldom used roadster that need to
pass state inspection, this fix did the job!

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles