Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 86Get this manual
CHECKING POSITIVE BRUSHES AND TERMINALS 1Connect ohmmeter (A scale) leads between positive brushes Brush Replacement
IMPORTANT: Replace brushes thai are pitted or
worn to less than 14 in(6.4mm) in length
2Ohmmeter must indicate full contin uity (zero resistance)lf resistance is indicated, check lead to positive terminal solder connection If connection cannot be repairedbrushes must be replaced Refer 10 "BRUSH REPLAC EMENT'11 660
aPositive Brushes
Positive (+) Terminal Long Brush Lead Push Lead Into Slot Insulating Washer Flat Washer Lock Washer Nut