What was found
INTEGRATED INFORMATION DISPLAY SYSTEM, (IIDS), DISPLAYED A "MINOR" ENGINE FAULT "TQ TRIM LVL L" FOR THE NR 1 ENGINE FROM THE DIGITAL ENGINE CONTROL UNIT (DECU). PILOTS CHECK FOR FAULTS FROM THE DECU AND THE IIDS. A MINOR FAULT WAS NOTED ON THE NR 1 ENG; "TQ. TRIM, LVL 1". FAULT OCCURRED ON THREE SEPARATE FLIGHTS IN AN INTERMITTENT FASHION. ON ALL THREE OCCURRENCES, ACFT DIVERTED AND RETURNED TO MX FACILITY. FIRST OCCURRENCE, TROUBLESHOOTING TOOK PLACE USING BOTH ENGINE AND ACFT MM. THE FAULT CLEARED ITSELF AND NO DEFINITIVE ACTION WAS TAKEN. SECOND OCCURRENCE, TROUBLESHOOTING AGAIN SHOWED NO DEFINED DEFECTS. TORQUE CONFIRMATION BOX WAS REPLACED. THIRD OCCURRENCE, "MINOR" FAULT ADDITIONAL TROUBLESHOOTING DETECTED EXCESSIVE VIBRATION OF THE NR 1 ENGINE. THE ENGINE WAS R & R WITH A 0.0 TSO, ENGINE ASSEMBLY.