What was found
THE PILOT REPORTED A ROUGH ENGINE IN FLIGHT AND RETURNED TO AIRPORT, A SAFE LANDING WAS MADE. MAINTENANCE GROUND RUN AIRCRAFT AND A FLUCTUATION IN FUEL FLOW WAS NOTED. THEY FOUND THAT THE MIXTURE CONTROL WAS STIFF WHEN MOVING. (POSSIBLE GALLING). FUEL CONTROL WAS REMOVED AND A NEW ONE INSTALLED, ENGINE WAS TRIMMED, TEST FLIGHT CHECKED NORMAL. FUEL CONTROL WAS SENT IN FOR WARRANTY.