wiper motor is kinda of a pain...its hard to get the arms off of it. then you pull the plastic cowl cover, then the motor will come out with the arms etc all attached. swap the motor and replace the stuff back in there.
i had mine go bad on me once, i went fishing with my boss and pulled his boat for him...we were almost home when a nasty storm hit, turned the wipers on and nothing. then i got them to work intermittently, finally a new motor fixed it.