As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED, COULD NOT LIFT THE LANDING GEAR LEVER AND THE LANDING GEAR WOULD NOT RETRACT. RETURNED TO KIAD AND LANDED WITHOUT INCIDENT. MAINTENANCE CLEANED AND LUBRICATED ALL PROXIMITY SWITCHES IN THE LANDING GEAR SYSTEM. OPERATIONAL CHECKS WERE GOOD WITH NO FURTHER DEFECTS NOTED.