I've been doing some pretty heavy loader work this winter - pushing snow plow furrows back and up into piles to maintain roadway width. I noticed my loader making an occasional noise or movement that disturbed me so I checked the 9 bolts on each mast. The 3 outer bolts on the left mast were slightly loose. I tightened them using a 24mm socket on a 1/2" drive breaker bar.
Just one more thing for you guys to be aware of in case it happens to you.