Just got an early 80's merc 25. Ran it on the muffs and didn't notice any shifting issues. On the water today and she had a hard time shifting into forward. When I got home I shifted into reverse and the prop locks. Nuteral spins freely, but when in forward it locks in one direction and spins by hand in the other direction. Any ideas? I imagine I need to drop the lower unit and see what looks funky. Mooch