Re: 96 Islander wiper motor switch/breaker?
no, that's a bad idea. multimeters are often on sale at Harbor Fright for <$5, and you'll need one if you're dealing with any old boat. if you have a spare taillight bulb, you could use that to test whether you have power to the motor.
don't think they use a "stop relay" like cars do to make the wipers stop at bottom of travel...mine just stops wherever the blade is when i kill switch.
my guess would be that your motor has old grease in it that's congealed to something like glue. if it is motor, try pulling it apart and cleaning with WD40, then re-greasing before you go looking for new motor. local starter/motor shop could probably rebuild it too if needed.