As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: BOTH WX RADAR INDICATE FAIL OF MFD. BOTH L AND R SYSTEMS IN FLIGHT. DECESION MADE TO RETURN TO JFK, EMERGENCY DECLARED. AIRCRAFT LANDED OVERWEIGHT AND WITHOUT INCIDENT. MAINTENANCE REPLACED WXR DRIVE UNIT AS PER M/M 34-43-03.