As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFT SERVICE DOOR VERY HARD TO OPERATE. COCKPIT INDICATION IS CYCLING ON AND OFF. SENSOR TARGET GUARD BROKEN OFF DURING TROUBLESHOOTING. FERRIED FOR REPAIRS. REMOVED FROM SERVICE. REINSTALLED TARGET GUARD IAW Q400 SRM 51-42-05. CYCLED DOOR OPENED AND CLOSED, DOOR OPERATED NORMALLY WITH GREEN INDICATION IN COCKPIT. NO FURTHER DEFECTS NOTED AT THIS TIME. OK FOR CONTINUED SERVICE.