What was found
CREW REPORTED SMOKE TOILET CAUTION MESSAGE DURING CRUISE. FLIGHT ATTENDANT CONFIRMED LAVATORY SMOKE ALARM SOUNDED. SMOKE WAS VISIBLE FROM ROW SIX (6) THROUGH 11. SMOKE TOILET QRH (QUICK REFERENCE HANDBOOK) WAS PERFORMED AND SMOKE DISSIPATED SHORTLY THEREAFTER. CREW DIVERTED AND MADE A SAFE LANDING. AIRCRAFT EVACUATED ON RUNWAY AND PASSENGERS BUSSED TO TERMINAL. MAINTENANCE INSPECTED, REMOVED AND REPLACED NUMBER THREE (3) CARBON SEAL ON LEFT ENGINE DUE TO EVIDENCE OF LEAKING AND PERFORMED CHECKS USING AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT RELEASED FOR SERVICE.