Struck against stationary object
SETUP AT NEW LOCATION. HE WAS LOOSENING THE BOLT THAT ALLOWS THE JACK LEG TO SWING DOWN. WHILE PULLING ON THE WRENCH THE FORCE OF IT BRAKING LOOSE CAUSED HIM TO STEP BACK & HIT HIS SHOULDER ON THE GUARD BEHIND HIM. AT FIRST HE HAD PAIN & THOUGHT IT WOULD IMPROVE BUT HE HAS DEVELOPED MORE PAIN & NUMBNESS & NOW NEEDS MEDICAL ATTN.