What was found
PIT FLT 268 ON CLIMB OUT FROM PIT, AT FL160, CREW REPORTED THE NR 1 ENGINE AGENT ONE DISCHARGE LIGHT ILLUMINATED. FLIGHT ATTENDANT REPORTED FLAMES OUT THE REAR OF THE ENGINE WHILE A DEADHEAD PILOT REPORTED EXCESSIVE VIBRATION. CREW DECLARED AN EMERGENCY AND RETURNED TO FIELD AT PIT. FLIGHT LANDED WITHOUT FURTHER INCIDENT AND TAXIED TO THE GATE. MAINTENANCE PERFORMED BOROSCOPE INSPECTION OF NR 1 ENGINE. NO DEFECTS NOTED. ACCOMPLISHED TROUBLESHOOTING TASK 73-00-00-02 AND REPLACED NR 1 ENGINE T3 SENSOR PER MM 77-23-10-04. RAN ENGINES AT VARIOUS POWER SETTINGS. ALL OPERATIONS NORMAL. ALSO, REMOVED AND REPLACED NR 1 ENGINE AGENT ONE DISCHARGE BOTTLE. OPS CHECK GOOD.