This is a pretty common problem. The center punch idea previously mentioned works good. I've not used body filler before, but Loctite 640 works very well:
http://www.emisupply.com/catalog/loc...term=LOC-37484
Another good option is to see if your local bike shop has a Stein Knurling tool, which is designed specifically for this issue:
http://www.ride-this.com/index.php/s...ource=googleps . If they do, they can knurl it for you in a matter of minutes for a few $.
Knurl it and loctite it and it will likely never come loose....
Dave