What was found
ON FLIGHT 3392 THE FLIGHT ATTENDANTS REPORTED THE MAIN CABIN DOOR WAS HARD TO OPEN, IT APPEARED TO CATCH ON THE UPPER LEFT CORNER. THE AIRCRAFT WAS REMOVED FROM SERVICE. INSTALLED 1 ADDITIONAL WASHER BETWEEN DOOR ARM FITTING NR 1 AND NR 2 PER ETN #EM-52-013R1 AND EMB 145-AMM 52-18-00. ADJUSTED FORWARD UPPER/LOWER BAR REF TO EMB AMM 52-18-00. THE OPERATIONAL CHECK WAS GOOD AT THIS TIME. THE AIRCRAFT WAS RETURNED TO SERVICE.