EMPLOYEE WAS TURNING THE ROTOR SHAFT IN ORDER TO CHANGE THE HAMMERS. WHEN THE ROTOR SHAFT MOVED FURTHER THAN INTENDED HE TRIED TO GET OUT OF THE WAY, BRUISING HIS RIGHT LEG AND DISLOCATING HIS LEFT SHOULDER. NOTE: SHOULDER HAD BEEN DISLOCATED PREVIOUSLY. DOCTOR SAID SHOULDER WAS UNSTABLE PRIOR TO ACCIDENT.