It's the only thing that annoys me about this car (1984 300D). The wipers chatter almost always. I've replaced them twice with Bosch wipers (including frames), but there was very little difference. After a full hour of rain, they'll sometimes settle down. Is there something mechanical that might be causing this?

It's supposed to rain all week - help!

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1984 300Sd 210k

Former cars:
1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break.
1993 300d 2.5 275k. Current 120/day commuter
1981 300SD 188k (Hans) Killed by a deer