2009 Yamaha F40 Outboard Service Manual, Page 334Get this manual
PTT motor
Checking the PTT motor
1Check the commutatorClean with 600 grit sandpaper and compressed air if dirty
Digital multimeter: YU-34899-A 4Check the bearingReplace the armature assembly if damaged
Checking the brush
1Measure the length of each brushReplace if below specification2Measure the commutator diameter aReplace the armature assembly if below specificationBrush standard length a: 7.5 mm (0.30 in) Wear limit b: 5.1 mm (0.20 in)