As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JFK - INFLIGHT BOS-STT. CREW REPORTED UNABLE TO MAINTAIN CABIN PRESSURE WITH RIGHT PACK AND LEFT PACK ON MEL. EMERGENCY DECLARED FLIGHT DIVERTED JFK LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT CABIN SUPPLY CHECK VALVE THAT WAS DEFECTIVE AND AFT CARGO DOOR SEAL. SYSTEM GROUND CHECK NORMAL OPERATION.