Last year I purchased a pontoon boat that has a 1975 75hp Evinrude Hustler motor. The motor runs great but at the end of the season (fortunately) I shifted into reverse and it stuck there. I finally got a round to playing with it yesterday and found that if I tip the motor up it shifts to forward, neutral, and reverse just fine. When I tip it down to it's running position when you shift to reverse it sticks. I have a manual that shows me how to remove the lower unit, but it's raining today I'm not going to pull it, but before I do, any ideas on where and what the problem is? Is this common for this engine?