As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENROUTE, THE FLIGHT CREW NOTED A STRONG ELECTRICAL ODOR AT FL 330 DURING CLIMB. FLIGHT RETURNED TO FIELD AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE PLACED THE AIRCRAFT ON MEL AND RELEASED FOR SERVICE. MAINTENANCE REPLACED THE EXTRACT VALVE. OPS CHECKED OK.