This sounds like a great solution, but here is another one...

On my 1992 300D I could not find the plastic teeth for sale (this was several years ago) but I did open up the wiper gear assembly from a 1985 190E and found the same teeth with one difference: the 190 gear teeth were bronze!.

I removed them from the 190, installed them in the 300, and greased it all up. It worked great.

Mercedes wanted $990 for the assembly.

Pooka