EE WAS CALIBRATING A CEMEMTN PACKING MACHINE. THE 2 CALIBRATION WEIGHT WERE 25KG EA. AND EE WAS LIFTING THEM OFF TOGETHER. AS HE WAS LIFTING THEM OFF THE CRADLE, HE TURNED TO HIS LEFT TO EXIT THE PACKER WHEN HE EXPERIENCED PAIN IN HIS LOWER LEFT BACK. HE PAUSED AND THEN CONTINUED TO WALK AROUND AND SET THE WEIGHTS DOWN. ANOTHER WORKER WAS WATCHING AND NOTICED EE WINCING IN PAIN.