As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THRU FL230 A LOUD BANG OCCURED AND A DROP IN POWER ON THE LEFT ENGINE WAS OBSERVED. RAN QRH 7.6 CONTACTED OCC AND MCC. RAN QRH 7.45 AND ELECTED TO LEAVE ENGINE RUNNING AT IDLE DUE TO NORMAL OIL PRESSURE AND LACK OF VIBRATION OR FURTHER ABNORMAL INDICATIONS. LANDED IN ATL WITH LEFT ENGINE AT IDLE POWER. REMOVED AND REPLACED THE NR 1 ENGINE.