EE WAS SEATED IN BAG SACKING CHAIR. BAGS FALL ONTO MOVING CONVEYOR 3' BELOW SEAT. WHILE STACKING BAGS COMING OFF SPOUT ONE WAS GOING TO FALL ON BAG PASSING UNDER ON CONVEYOR. AS SADDLE THAT SU PPORTS BAG WHILE FILLING, TIPPED BACK TO DISCHARE BAG, EE REACHED TO STOP BAG. STRAINED LEFT SHOULDER. EE DID NOT REPORT INCIDENT UNTIL 9/8 & SAW DR 9/11/00.