What was found
BWI - FLT 2829 - EN ROUTE FROM BOS TO FLL, AT FL 260, FLIGHT ATTENDANT ADVISDED CREW OF A LOUD SQUEAL FROM THE AFT LEFT SERVICE DOOR. FIRST OFFICER WENT BACK TO LOOK AT DOOR. PRESSURIZATION WAS FINE BUT NOISE WAS TOO LOUD TO CONTINUE ON TO FLL. FLIGHT DIVERTED TO BWI AND LANDED WITHOUT FURTHER INCIDENT. AIRCRAFT TAXIED TO THE GATE ON ITS OWN POWER. NO EMERGENCY WAS DECLARED. MAINTENANCE LUBED THE AFT LEFT SERVICE DOOR SEAL. PRESSURIZED AIRCRAFT. LEAK AND OPERATIONAL CHECK GOOD. (M)