I have a early to mid 70's 25hp Evinrude outboard on my fishing boat. No steering wheel you just drive it with the handle on the motor. Until the past year it has sat. We got it running and it worked fine until this year. Now when you put it into gear it jumps out into neutral. The only way to be able to move is to keep it at a slow idle and hold the lever in forward with your hand. If you let go and especially when you try to go faster it jumps out. What could this be and how can it be fixed? Any info is greatly appreciated thanks.