Well, I went to the local Ace hardware, didn't have a nut, LBS wasn't open yet. But I did compare the serrations on a new nut to the one I had and the new nuts serrations seemed to be a lot sharper and well defined. So I brought the old nut home and just touched the edge of each serration with the Dremel cutoff wheel just to freshen the edge a little. The I used some blue (read: removable) Loctite on the threads. We'll see how this goes. If not I'll replace the nut, and if necessary the crank arm. I gotta tell you though when the arm is installed there isn't the slightest amount of wiggle or movement in it at all. Solid as I could imagine it would be. Time will tell, thanks for the tips.