Doug, I've run Merc. 9.9's for a few years on charter boats and can tell you that the locking mechanisms are a week point on these motors. I strictly motor-mooched and sometimes in rather rough condition where I had to run the kicker pretty hard in reverse, there is a plastic piece that will break, I broke 3 to 5 every season (4 months) once it breaks the motor will not stay down at much more then idle speed in reverse. I've run Yamaha's and an old Evinrude in the same conditions and never had a problem.