Quote Originally Posted by aston_jag_tech
The regulator does not need to be replaced if the brushes are less than 5mm. The regulator cost to buy is 174 dollars. brushes are about 37 dollars. You do need to solder them in though. After you install new ones, take it to autozone, pep boys, or if you know of a friend with an alternator tester, check it out. Piece of cake.
they have the regulators with new brushes for $25.72 (1990 535i M30).