As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF, HAD A REDUCTION IN FUEL FLOW, LANDED WITHOUT INCIDENT. UPON INSPECTION IT WAS NOTICED THAT THE RETAINING LOCKNUT FOR THE MIXTURE CONTROL LEVER HAD BACKED OFF THE LEVER CAUSING THE LEVER TO COME OUT OF RIG AND STRIP THE SPLINES OFF THE LEVER. THE TECH INSTALLED A O/H FUEL CONTROL, NEW LEVER AND NEW LOCKING NUT.