As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF IN DTW, THE GEAR UNSAFE LIGHT WOULD NOT EXTINGUISH AFTER THE GEAR WAS RETRACTED. FOLLOWED QRH AND THE GEAR WOULD STILL NOT RETRACT. ALL HYDRAULIC INDICATIONS NORMAL. AIR RETURN TO DTW. MAINTENANCE CLEANED AND SWUNG GEAR. LUBED SQUAT SWITCHES. ALL CHECKS GOOD IAW SF340 MM CHAP, 32.