1993 Johnson Evinrude "ET" Electric Outboards Service Manual, P/N 508280, Page 113Get this manual
Cleaning and Inspection 1Inspect the brushes, and replace them if they are less than (9 mm) longReplace brush springs if damaged3 8
2Clean commutator with 300 grade emery clothIf commutator surface is unevenly worn or pitted, turn it in latheRemove any trace of oil or metal dust from the commutator[]]]3Check armature for shorted turns on growlerCheck armature for grounding using test light or meterInspect armature insulation for indications of overheating or damaged windingsClean off any deposits of carbon or foreign matter which might contribute to later failure of the windings4Check permanent magnetsMagnets should strongly attract any steel or iron object held inside the field assemblyMagnets must not be cracked or have any pieces missing