Rock was stuck in grizzle bars. Loader Operator feed large rock to dislodge. Rock did not dislodge. EE got into the feeder with a sledgehammer to dislodge the jammed rock has EE swung the hammer EE missed the rock and struck the grizzle bars which caused the hammer to ricochet causing EE to lose EE's balance and falling approximately 18 to 20 ft.