Does the starter get exposed to long crank times? Or does the engine fire up within 10 seconds all the time? Even ten seconds is a long time for a starter to run.
Have you looked at the flywheel to see if you have any missing teeth?
No teeth missing on flywheel..flywheel is (new) Found out that the "planatary gear is bad this was in all 3 starters all bad. makes no sense for the planatary gear to keep going out unless its just bad starters!..they say theres 2 happiest days of your life.."the day you buy a boat and the day you sell it"..lol