Hello, I have been reading the forum for some time, but now have a question that I have not been able to resolve on my own.

I have two W124 300D's.

The uni-wiper on my '87 started to slow a bit on portions of it's sweep. On the advice of a master Mercedes mechanic, I used a product called Tri-Flo on the obvious moving parts. Which fixed (for now) the problem.

Then I got to noticing a difference between wipers on my two W124's: on the car that had the problem, there was very heavy/obvious rub/wear between the long cover (just above the "turtle shell" hub) and the arm. The part the moves in and out, just above the center hub.

The other car, no wear at all in this area. Appears to not touch at all.

Is it normal for these two parts to rub on each other?