2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 178Get this manual
Power trim and tilt motor 5Check the circuit breaker for continuityReplace if there is no continuity Commutator diameter wear limit: 21.0 mm (0.83 in) 3Measure the commutator undercut aReplace the armature if below specification6Measure the brush lengthReplace if below specification
Brush length wear limit e: 3.5 mm (0.14 in) Commutator undercut wear limit a: 1.0 mm (0.04 in) 4Check the armature for continuityReplace if out of specifications7Check the base for cracks or damageReplace if necessary8Check the bushing and oil seal for damage or wearReplace if necessary