As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE#1 N2 REACH AMBER BAND DURING CRUISE THRUST WAS REDUCED AT APROX 80%, THERE WAS SURGE ON THE ENGINE AND VIBRATION OF 3.0, THRUST WAS FURTHER REDUCED AND STABILIZED AT 70% N1. CORRECTIVE ACTION REMOVED AND REPLACED MAIN ENGINE CONTROL.