We had to take that Christmas ride this afternoon. Got about 1/2 mile from home and the motor starts to sputter, it's a 15hp Evinrude. So I idle down then she stops and I couldn't get it to turn over. Pull the cover and can spin the flywheel about 3/4s of a turn and that's it. So I kept going back and forth and finally was able to get it to spin freely. Got it started and ran home and pulled the spark plugs. Bottom plug was covered with aluminum shavings.
Well it looks like I'll be spending Christmas tearing the motor down to see what it ate.