As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDING GEAR WOULD NOT RETRACT. FLIGHT RETURNED & LANDED WITHOUT INCIDENT. ACFT REMOVED FROM SERVICE. PERFORMED GEAR RETRACTION & EXTENSION WITH NO FAULTS NOTED. CLOSED ALTERNATE EXTEND DOOR THAT WAS FOUND OPEN. SYS GND CHECKED NORMAL OPERATION CLOSED.