Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 90Get this manual
Starter Cleaning, Inspection and Testing CLEANING AND INSPECTION
1Clean all starter motor parts2Check pinion teeth for chips, cracks or excessive wear3Replace the drive clutch spring andor collar if tension is not adequate or if wear is excessive4Inspect brush holder for damage or for failure to hold brushes against commutator5Replace brushes that are pitted or worn to less than 14 in(6.4mm) in length6Inspect the armature conductor (commutator bar junction) for tight connectionA loose connection (excessive heat from prolonged cranking melts solder joints) results in burned commutator bar7Resurface and undercut rough commutator as follows:
8Open-circuited armatures often can be repairedThe most likely place for an open circuit is at the commutator bars, as result of long cranking periodsLong cranking periods overheat the starter motor so that solder in the connections melts and is thrown outThe resulting poor connections then cause arcing and burning of the commutator bars9Repair bars, that are not excessively burned, by resoldering the leads in bars (using rosin flux solder) and turning down the commutator in lathe to remove burned material, then undercut the mica10Clean out the copper or brush dust from slots between the commutator bars11Check the armature for groundSee the following procedure ("Testing")