As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BURNING PLASTIC ODOR IN CABIN AFT OF ROW 20. SUSPECT DUCT OVERHEAT IN ZONE E. ACCOMPLISHED CTC LT AND RT MAT TESTS. BOTH PASSED. RAN PACKS AND FOUND ZONE E TRIM AIR VALVE NOT OPERATING TO FULL CLOSED POSITION. DF PER MEL. PROBLEM RECURRED NEAR ROW 20. COULD NOT DUPLICATE, ALL SYSTEMS OP NORMAL. NO ODORS FOUND.