As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENROUTE AT 25,000 FT, THERE WAS A LOUD SQUEAL FROM THE TYPE II/III EXIT DOOR ON THE FO'S SIDE. RETURNED TO FIELD, LANDING UNEVENTFUL. R & R RT FWD LOWER EMERGENCY EXIT DOOR SEAL IAW MM TASK 52-23-06-000-801 AND TASK 52-23-06-400-801. PRESSURIZATION LEAK CHECKED GOOD. NO LEAKS OR NOISE DETECTED. RETURNED TO SERVICE.