As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD CREW REPORTED LOUD AIR NOISE WAS COMING FROM NLG AREA ALONG WITH RED UNSAFE INDICATION. FLIGHT RETURNED ORD LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. ADJUSTED NOSE LINKAGE TO GET TARGETS IN RANGE. SYSTEM GND CHECKED NORMAL OPERATION CLOSED.