2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 96Get this manual
ELECTRICAL STARTER MOTOR Use vernier calipers to check the length of each brush If any brushes are worn below the service limit, they must be replaced Brush Length 0.49 in(12.5 mm) Standard 0.35 in(9 .0 mm) Service Limit I
Assembly
Install the brush holder assembly in the rear coverInstall and tighten the screws securelyInstall new O-ring, the plastic washer, two (2) washers, and the nut that secures the brush holder to the rear cover