Windshield Wiper/washer Linkages problems of the 2003 Chevrolet S10

Both wiper blades chatter on windshield of 2003 s-10. They do not wipe water off of windshield making it very difficult to see in rain or snow. This happens while driving or standing still but moving makes it worse. This vehicle was bought new in July of 03. Also owned a 98 s-10 that did the same thing. Dealers say that is just the way it is. I work for a tier 1 wiper systems manufacturer and test these things. That is not how they are supposed to work. This is a big safety issue. Very unhappy with the dealer's reaction. Ng, indiana.