I dont know how pratical this is for you but if a wheel is dragging, jack up that WHEEL AND CRACK OPEN THAt calipers bleed screw. If the wheel quickly frees up its not the caliper but the hose to it. Change both and flush the system.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.