2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 95Get this manual
ELECTRICAL STARTER MOTOR Use vernier calipers to measure the commutator outside diameterIf the measurement is less than the service limitreplace the armature&
WARNING
Commutator Outside Diameter Standard 1.18 in(30 mm) 1.14 in (29 mm) Service Limit I
To avoid personal injury, wear eye protection and set compressed air pressure to less than 25 psi (172 kPa)Use compressed air to remove all particles of mica and metal from the armatureCheck for continuity between the commutator and the armature core and shaftReplace the armature if continuity is indicated