Honda BF35A-BF45A Outboard Motors Shop Manual., Page 198Get this manual
SHORT CIRCUIT TEST-CORE-TO-COMMUTATOR Check for continuity between the commutator and armature coil coreIf continuity exists, replace the armature SHORT CIRCUIT TEST-SHAFT-TO-COMMUTATOR Check for continuity between the commutator and amature shaftIf there is continuity, replace the armature
SHORT CIRCUIT TEST-ARMATURE Place the armature in an armature tester (commercially available)Hold hacksaw blade close the armature coreIf the blade is attracted the core or vibrates when the core is turned, the armature is shortedReplace the armature