Buy a whole new blade, not just the insert. They get weak with age and loose their "spring", so the outside doesn't wipe well. They also wear at the connection link, and start to thump and slap.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!