The brushes are part of the regulator. An auto parts store generally cannt separate a faulty regulator from a faulty alternator during the test. Regulators are rather inexpensive in relation to a replacement alternator. And truth be told, most rebuilts are just a new regulator and maybe a set of bearings.

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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.