I had problems with a chattering wiper in my 1995 E420 - drove me nuts. I kept having to switch the wiper on and off manually, because at the normal intermittent setting the niose was very annoying.

I read about teflon wiper blades being a possible solution, and bough one at Advance Auto parts (the entire assembly - not just blade). No chattering since. I've also put rain-x on the windshield, which is great - really reduces the need for using the wipers, especially at higher speeds. The rain just flies off the windshield by itself.

Troy
1995 E420 87k