MY GUESS IS THE CLAMP UNIT THAT HOLDS THE END OF SHIFT CABLE. CABLE HAS SLIPPED OUT ONLY NEEDS TO BE PUT BACK IN. I SEE IT HAPPEN MORE THAN A FEW TIMES. BUT IF YOU WERE RUNNING BOAT HARD THE CLUTCH CAN STICK IN THE CUP. AT THAT POINT THE SHIFTER CABLE WOULD BE IN REVERSE POSITION AND NOT MOVE.( OR BROKEN SHIFT CABLE!!!) LET US KNOW WHEN YOU PULL THE DRIVE GOOD LUCK RON:)

Formula Outlaw
I had that happen to my drive also. but, my cone clutch welded up while in foreward. All I had was foreward, no nutral or reverse. I left one engine off while backing up. Then started the other when I went foreward and drove home.
A friend had his lock in reverse that same weekend. His trouble was what I discribed above.

I don't understand how it could weldup in reverse. I was told it was because of the older style cone clutches and too high of rpm.
I guess not always.

Yeah, I had only been idling around, pulled up to my sector captains boat, shifted into reverse to back up a little, yelled something at him, shifted back to forward, but only the starboard drive went forward. Like I said, that stupid "ring" had broken off and slid down, preventing the clutch cone from moving. No other damage done, but I still ended up doing to whole top gear assembly, etc. Sucked. Wife was REAL happy.