I know some will jump me on this but I used red loctite on mine and they have never loosened up. I just used a small amount of it. We have 3 at the field and we have all done this.

You could also use the trick we use with our Moki's. Drop some dowels into holes to length and put a metal band clamp across it this way it CANT come out. It just looks like crap. And its Band CLAMP.. not band camp