As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SURFACE CORROSION, FLAP TRACK NR 4 ROLLER WAY. THIS DOCUMENT PROVIDES REPAIR INSTRUCTIONS FOR CORROSION DAMAGE FOUND ON THE NR 4 FLAP TRACK LOWER ROLLER WAY SURFACES. BLENDED OUT THE CORROSION PER OHM PROCEDURES WHILE MAINTAINING THE DRAWING FLATNESS AND PERPENDICULARITY REQUIREMENTS. THIS REPAIR IS APPROVED BY THE BOEING COMPANY PER ECRA N639FE-57-B747-006-EAC.