As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. DIRTY SOCK SMELL NOTICED ON TAXI OUT WITH APU NOT IN USE, DURING INITIAL CLIMB, AT CRUISE AFTER TURNING ON ANTI-ICE, AND AFTER START OF DESCENT. ACCOMPLISHED CABIN ODOR TROUBLESHOOTING PER MCM CARD 05-96-70, NO ODOR NOTED. REMOVED AND REPLACED LEFT RECIRCULATION AIR FILTER PER AMM 21-25-01 AT MOC REQUEST. OPERATIONAL CHECK GOOD.