EMPLOYEE WAS REMOVING BOLTS ON 801 HYDRAULIC FILTER HOUSING WITH 1/2 INCH DRIVE RATCHETT. THE BOLTS WERE VERY TIGHT AND THE LOCKING MECHANISM IN THE RATCHETT DID NOT HOLD. WHEN THE RATCHETT SLIPPED HE FELT SOMETHING PULL IN HIS RIGHT SHOULDER. HE CONTINUED TO WORK AND THE PAIN BECAME WORSE.