Windshield Wiper Chatter
What makes new windshield wiper blades chatter on a clean windshield?
Forum Discussion
The other possibility is that the springs in the wiper arms are weakening and not keep proper tension on the blade. Not even sure how you would check that, but we had a wiper that did that on one of our vehicles and by chance (meaning a limb managed to fall and hit right on the wiper arm bending it badly), had to replace the wiper arm and the problem went away. If all else fails, you might look at them.
