As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: WHILE IN CRUISE, PRESSURIZATION FLUCTUATES + OR - 750 FPM WITH SYSTEMS 1 AND 2. MAINTENANCE PERFORMED A SATISFACTORY OPERATIONAL CHECK OF CABIN PRESSURE CONTROLLERS #1 AND #2 WITH NO FAULTS NOTED OR RECORDED. AS A PRECAUTIONARY MEASURE MAINTENANCE CLEANED THE RUBBER SEAL ON THE OUT FLOW VALVE.