As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RADAR SHOWED FALSE RETURNS IN AUTO MODE ONLY. RETURNS WERE FROM 9 O'CLOCK TO 11 O'CLOCK POSITION 40 TO 80 MILES. GROUNDED - YES. DUE TO HISTORY, REMOVED AND REPLACED WEATHER RADAR ANTENNA DRIVE UNIT REF B737-900 AMM 34-43-11. PERFORMED OPERATIONAL TEST OF WEATHER RADAR SYSTEM REF AMM 34-43-00-710-802-001. OP CHECK GOOD. ETOPS GROUND VERIFICATION SUCCESSFUL.