As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF UPON LANDING GEAR RETRACTION, GEAR WULD NOT RETRACT. AIRCRAFT RETURNED TO MSP AND LANDED WITHOUT INCIDENT. CLEANED AND REMOVED DINOL FROM LANDING GEAR SELECTOR VALVE AND PERFORMED FUNCTIONAL CHECK OF LANDING GEAR SYSTEM AND VALVES. OPERATIONAL CHECK OK.