1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 332Get this manual
CHECKING AND CLEANING COMMUTATOR
If commutator is worn it can be turned down on an armature conditioner tool or on latheClean commutator with "00" sandpaper
1Install check valve components into pump manifoldIMPORTANT: Sleeve (d) is chamfered on I.Don end opposite drilled cross holeInstall spool (e) (with O-ring installed) from chamfered end of sleeve to avoid possibility of damaging O-ring on spool
aCommutator