1991 Johnson/Evinrude EI 60 thru 70 outboards Service Manual, Page 244Get this manual
Cleaning and Inspection 1Inspect the brushes; replace if one-half worn, damaged, or cracked Replace brush springs, if weak 2Clean commutator with 300 grade emery clothIf commutator surface is unevenly worn or pitted, turn on latheRemove any trace of oil or metal dust from commutator Check the armature on growler for shorted turnsCheck armature for grounding by using test light or meterInspect armature insulation for indications of overheating or damaged windingsClean off any deposits of carbon or foreign matter which may contribute to later failure of the windings[