What was found
PILOTS NOTICED VIBRATION ASSOCIATED WITH THE NR 1 ENGINE. TECHNICIAN LOCATED SOURCE OF VIBRATION AS NR 1 STARTER/GENERATOR. THIS UNIT HAD BEEN REMOVED AND REINSTALLED TWO WEEKS PRIOR TO VIBRATION AFTER REBRUSHING BY AN OUTSIDE FACILITY. UNIT ACCUMULATED 70 HOURS AFTER REBRUSHING PRIOR TO FAILURE. TECHNICIAN SUSPECTS FAILED BEARING DUE TO THE SEVERE SIDE PLAY IN THE STARTER/GENERATOR SHAFT, WHICH SET UP SUFFICIENT VIBRATION TO CAUSE COMPLETE FAILURE AND SEPARATION OF THE GEARBOX TO ENGINE SUPPORT BRACKET FITTINGS ON THE GEARBOX.