What was found
AFTER TAKEOFF, FLIGHT ATTENDANT 2 & 4 REPORTED A RUBBER ODOR, BUT DISSIPATED. APPROX 40 MINUTES INTO FLIGHT, FLIGHT ATTENDANTS REPORTED EXCESSIVE NOISE & VIBRATION FROM ROW 33 & PROGRESSED AFT. ENG PARAMETERS WERE NOTED ON TREND AFTER AUTO-THROTTLES WERE TURNED OFF. POWER WAS SLIGHTLY REDUCED & FLIGHT ATTENDANT REPORTED LESS VIBRATION & VIBRATION POINT WASN'T FELT UNTIL ROW 36 & AFT. PERFORM VIBRATION CHECK IAW AMM 72-00-05. TROUBLESHOOT STEPS 1 - 16, NO DEFECTS NOTED. PERFORMED VIBRATION CHECK TROUBLESHOOTING STEPS 17 - 20. NR 1 ENG N1 AVG 1.8 MILS WITH SPIKES TO 2.7 MILS, N2 AVG WAS 1.0 MILS WITH SPIKES TO 1.4 MILS. NR 2 ENG N1 AVG 1.2 MILS WITH SPIKES TO 1.5 MILS, N2 AVG WAS 1.0 MILS WITH SPIKES TO 1.3 MILS. VIBRATION CHECK, TROUBLESHOOTING COMPLETED. VIBRATION WITHIN LIMITS IAW AMM 72-00-05.