1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 52Get this manual
14Measure the armature shaft for deflectionIf the armature has greater than 0.002 in(0.05 rnrn) deflection, replace armature 17After cleaning, ohm test each segment of the commutator as shownIf ohm test reading is other than listed, replace the armature
aArmatureV-BlockDial Indicator Gauge
ARMATURE COIL CONTINUITY METER TEST LEADS RED SEGMENT BLACK SEGMENT METER SCALE
READING CONTINUITY
15Measure the commutator diameterReplace if not within specification
bCommutator Diameter Wear Limit1.22 in(31.0 mm)