As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 7820, ENROUTE MSO-GTF AIR TURNBACK/DISCREPANCY: LANDING GEAR FAILED TO RETRACT ON CLIMB OUT. AIRCRAFT WAS RETURNED TO MSO. LANDED SAFELY AND NO EMERGENCY WAS DECLARED. MAINTENANCE DEFERRED THE ISSUE AND AIRCRAFT WAS RETURNED TO SERVICE. DEFERRAL WAS CLEARED BY REPLACING THE 55GB PROXIMITY SWITCH.