The vents you cleaned out are NOT the rear sun roof drains. They are to exhaust air from the interior. The drains are hoses that exit the body just behind the rear tires. Hoses can be seen in the trunk with the inner trunk liners removed. The CHOKE cable should work in theory but simply depressing the throttle partially when started cold will do much the same thing. That cable broke because the PO did not depress the throttle slightly before twisting the dash knob.

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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.