I was going along just fine in forward planing doing about 25mph when all of a sudden with no warning the engine started reving and the boat came to a stop. Like it popped out of gear. I tried to put it back in gear but the motor just revs. It will go into reverse though. When i shift the motor i can see the shift shaft turning and i can see the machanism under the cover moving. So do you have any suggestions? Where do I start?