As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 7542 IAD TO YUL - DURING CLIMBOUT AND DURING CRUISE CREW REPORTED AN NR 2 ENG LP SPOOL VIBE 4.1 DURING CLIMB AND WENT TO 4.0 AT CRUISE. PERFORMED QRH PROCEDURE AND RETURNED TO FIELD. OCM REMOVED AND REPLACED FWD ACCELEROMETER. PERFORMED ENGINE RUNS AT ALL POWER SETTINGS TO INCLUDE TOGA, NO ABNORMAL VIBES DETECTED. DISCREPANCY REPEATED 03/27/2007. FERRIED TO IND. MAINT ACCOMPLISHED BLADE LUBE AND INSTALLED NEW BLADE BUMPERS.