As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX-LEFT MAIN GEAR DOOR CYCLING IN FLIGHT. LEFT GEAR DOOR LIGHT WOULD ILLUMINATE AND BE ACCOMPANIED BY A SLIGHT VIBRATION. REMOVED AND REPLACED LEFT HAND MAIN LANDING GEAR UPLOCK PROXIMITY SENSOR. OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.