Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 85Get this manual
Cleaning and Inspection 1Clean aU motor parts2Check pinion teeth for chips, cracks or excessive
Testing
ARMATURE TEST FOR SHORTS Check armature for short ci rcuits by placing on growler and holding hack saw blade over armature core while armature is rotatedIf saw blade vibrates, armature is shortedRe-check after cleaning between commutator barsIf saw blade still vibrates, replace armatu re
wear3Replace th drive clutch spring andlor collar, if tension is not adequateor jf wear is excessive4Check that the brush holder is not damaged or is not holding the brushes against the commutator
5Replace brushes that are pitted or worn to less than 14 in(6.4mm) in lengthRefer to "BRUSH
REPLACEMENT', following6Replace damaged or excessively worn bushing in the end cap
7Check the armature conductor (commutator bar
junction) for firm connection poor connection usually results in burned commutator barBRe-surface and undercut rough commutator, as follows;
A CAUTION
Do not turn down the commutator excessivelyaRe-surface the commutator and undercut the