I just had the same problem. All last year could hear the motor running but nothing out of the starboard side tab checked all the connections without luck. This winter I was ready to replace the actuator but decided to have a friend manually push down on the tab (it was stuck all the way up) as I used the control, miracle it started to work again. There was minor corrosion on the shaft, cleaned it up, coated it with grease and has been working for almost 6 weeks now without an issue.
Moral of the story, before you pull the boat or make yourself crazy like I did all last year try this, it can't hurt.