As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCN - DURING C19 CHECK DISCOVERED CORROSION AROUND SILL WEB NUT PLATES ON TORQUE BOX AT AFT PIT DOOR CUTOUT BETWEEN BS 795 TO BS 847 AND AT STR 25R. CORROSION WAS FOUND TO BE OUT OF LIMITS IAW BOEING 737-300 SRM 53-60-15-1A1 FIG 101. MAINTENANCE REMOVED AND INSTALLED NEW SILL WEB WITH NEW NUTPLATES ONTO TORQUE BOX AT AFT PIT DOOR CUTOUT IAW BOEING 737-300 SRM 51-40-02-0G FIGS 3, 9, AND 10.