As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5196 - AIRCRAFT CABIN AT 500FT/MIN THEN STOPPED CLIMBING AND CABIN ALT STOPPED AT 6000 FT. LEVEL AT FLT 10 PERFORMED QRH PROCEDURE AB2-5 AND RETURNED TO LGA AND LANDED SAFELY. PERFORMED OPS CHECK OF BOTH CABIN PRESSURE CONTROLLERS. AIRCRAFT PRESSURIZED NORMAL.