1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 41Get this manual
Starter Cleaning, Inspecting, and Testing ARMATURE Inspecting and Cleaning Armature
ICh eck bend ix dri ve teeth for hips, cracks or wear2Check arma ture for bent or worn shafts scored core laminations, or unsoldered connections3If commutator is roughburned or wor it ca be turned clown all 8n armature co ndi tioner 1001 or on lathe as follows:
Armature Test for Ground
Using an Ohmmete (Ihl scale)place one lead on armaturc core or shaft and othcr lead alt rnatel on commutat seg me nt s(Figure 5) If metc indicates continuit yarmature is grounded and mu st he re pla ced
ACAUTION
Do not turn down the commutator excessively
aTurn Ihe commutator down an unde rc ut th insulation between the commutator bars 1 32" (O.8mmJ to the full width or th insu lation and so Ihal the undercut is flatbClean he commutator S101 after unde rclI1IingcSand th commutator lighrl wilb No00 sandpaper to remo ve burrsthen clea th com mutator4, commutat is dirt y, sa nd he co mmutator with No00 sandpape rth clean the commutator