ROCK GOT STUCK UNDERNEATH SLIDE DOOR FROM FEEDER HOPPER TO FEEDER THROAT. EE ATTEMPTED TO DISLODGE ROCK, USING 6' SPUD BAR. PLATE THAT EE WAS STANDING ON GAVE WAY, CAUSING HIS BODY TO DROP APPROX. 6"". EE LOST HIS BALANCE, THE SPUD BAR MISSED THE TARGET AND STRUCK THE DOOR, BOUNCING BACK AND STRIKING EE'S SAFETY GLASSES ON RIGHT SIDE OF FACE, CAUSING INJURY.