It came from an old thread but this bright idea really helped me

[124Addict]

Originally Posted by Benz240D

I cannot believe you guys! Stand back, look at the ANGLE of the wiper resting on the windshield.

I don't care if you have a Chevy Chevette or a Ford Pinto or a Rolls Royce, That wiper arm gets tired! And so does that Angle of the part that you attach that new wiper to. Bend it back straight, then tell me how great that wiper works again!

That wiper is setting there in the Hot sun, day after day. It gets used how much in the life-time of the car? Not much.
Sun and heat does things to metal.

Yes, replacing the wiper arm is always the easiet way, but it is also the most expensive way too.

My wife complained her 96 Crown Vic wasn't cleaning winshield right and chattering, I bent the thing straight, works like new! Same Blades! Same Wiper Arm!

I tried the "bending it straight" technique and it really works. No need to buy new blades nor put anything on the windshield. Visual inspection of the arms left me aghast looking how skewed it was. Since it was twisted it keeps the blades from standing perpendicular to the windshield, thus the chatter. It is now as quiet as it can be. No more chatter at totally no cost. Hooooray!!!

This is a simple DIY and a great information. For those who are using the search engine, keep on using it. You might just find the answer to your problems with your Mercs.