This is what happened.I took the Cover off just checking things. The Pully had ben rubbing the cover I never heard it but i had been riding pretty hard I called the local dealer they told me what to tourque it to, and 5 miles later I had to trailer it home. I looked at my Stratoliner Couldn't tell anything by looking.
That bottom pic from linerdave's link is the part you want to peen it into that groove.
Blue loctite doesn't hurt either if you still have trouble with it. At Least it will come off when needed. Just requires torque not like the red that needs heat.
Just so you will know. the nut had been loose too long I guess. any way $800.00 fix at Yamaha. They told me the nut should be checked every 4000 miles.. its eay to get to so check yours and save some money.