EE WAS CLIMBING UP STEPS TO 980C LOADER. HE WAS CARRYING GREASE GUN AND 3 TUBES OF GREASE. ON 2ND STEP UP HE LOST HIS BALANCE AND FELL BACK LANDING ON HIS DERRIERE. THE NEXT DAY HE HAD OCCATIO NAL BACK PAIN AND THE 2ND DAY (SAT) HE WAS UNABLE TO WALK COMFORTABLY.