1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 263Get this manual
Cleaning and Inspection 1Inspect the brushes; replace if one-half worn, damaged, or crackedReplace brush springs, if weak2Clean commutator with 300 grade emery cloth If commutator surface is unevenly worn or pitted, turn on latheRemove any trace of 0;1 or metal dust from commutator
3 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 windings4Check permanent magnetsMagnets should strongly attract any steel or iron object held inside the frame Weak magnets will cause excessive rpm on No Load Current Draw, Electric Sta rt er test5Do not clean the starter drive assembly while the starter motor and drive are installed on the powerheadThe cleaning agent could drain into the starter motor, washing dirt from the drive into the starter bearings and commutatorAfter disassembling the drive, clean each part with grease solvent and inspect for wear or distortion