As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE NUMBER ONE LEADING EDGE FLAP FAILED TO RETRACT AFTER TAKEOFF, AIRCRAFT RETURNED TO BASE. THE NUMBER ONE LEADING EDGE FLAP POSITION SWITCH AND ACTUATOR CANNON PLUG WERE CLEANED. PERFORMED ADJUSTMENT\TEST PER BOEING MAINTENANCE MANUAL AND FLAP TESTED GOOD.