As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DTW-YUL - FLT 9203 - WHILE CRUISING AT 33,000 FEET, THE CABIN PRESSURE STARTED TO RISE. AN EMERGENCY DESCENT WAS INITIATED AND REVERTED TO MANUAL PRESSURIZATION CONTROL. THE CABIN PRESSURE WAS CONTROLLED AT 18,000 FEET. THE AIRCRAFT DIVERTED TO PIT AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE LEFT THRUST REVERSER SECTOR SEAL. (M)