Mercury Mariner Service Manual 6, 8, 9.9 210CC Sailpower, Page 31Get this manual
CHECKING MOTOR ARMATURE for GROUND 1Use an ohmmeter (R 100 scale) to check for "no continuity" between commutator and armature core or commutator and shaft2If "continuity" exists between commutator and armature core (or shaft)armature is grounded and must be replaced
Starter Motor Reassembly