As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: DOOR 4L WILL NOT ARM. HANDLE WILL NOT MOVE. MAINTENANCE FOUND A NUT STUCK ON ARMING GIRT BAR RECEPTACLE AND REMOVED AND LUBED. NOW DOOR ARMING IS VERY SMOOTH. IT WAS ALSO VERIFIED BY FLIGHT ATTENDANCE. AMM 52-10-00 OPERATION TEST OF ESCAPE SLIDE.