What was found
OWNER COMPLAINED THAT THE AIRCRAFT WOULD NOT SHUT DOWN USING THE MIXTURE CONTROL. MAINTENANCE PERFORMED ENGINE RUN, NORMAL. PERFORMED ONE MORE RUN AND COULD NOT SHUT DOWN USING MIXTURE CONTROL. TROUBLESHOT SYSTEM, FOUND ALL 4 SCREWS HOLDING THE 2 HALVES OF THE CARBURETOR VERY LOOSE. THE LOCKING TABS WERE IN PLACE. AFTER REMOVAL OF THE CARB, ALL THE FUEL IN IT COULD BE POURED OUT OF THE PARTING FLANGE.