As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE MIXTURE CONTROL SHAFT ON THE ENGINE DRIVEN FUEL PUMP FROZE UP AT HALF TRAVEL BETWEEN FULL RICH AND IDLE CUT OFF. THIS CREATED A LEAN MIXTURE CONTROL WAS DISCONNECTED FROM THE FUEL PUMP, THEN THE FUEL PUMP CONTROL SHAFT HAD TO BE FREED UP. THE MIXTURE CABLE WAS COMPLETELY FREE WITH NO BINDING ONCE DISCONNECTED FRO THE FUEL PUMP. THE FUEL PUMP WAS REPLACED AND SENT BACK TO MFG. (K)