2 OPERATORS PROCESSING DRUMMED MATERIAL INTO DISPERSION TANK WITH HIGH SPEED MIXER. MIXER MOVED TOO FAR. OPERATORS PUSHED AGAINST HEAD OF MIXER TO MOVE IT BACK TO NORMAL OPERATING POSITION. OPERATOR THEN NOTICED DISCOMFORT. OPERATOR SAW DR. ON SEPT. 6, 2001. CONDITION AGGRIVATED. WENTTO REGULAR DR. ON 10/03/01- ON 10/09/01 TOLD NOTTO WORK.