As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN RATE OF CLIMB INDICATOR MOVING CONSTANTLY BETWEEN + AND - PRESSURE, K UP TO +500, -700 FPM. CABIN DIFF PRESS CONSTANT AND NORMAL. NO PHYSIOLOGICAL EFFECTS. CABIN CLIMB WAS NORMAL AT 10K AND 18K. GROUNDED-YES. REMOVED & REPLACED OUTFLOW VALVE. GROUND VERIFIED GOOD, NO DEFECTS NOTED, REF B737-900 AMM 21-31-03-00-801 & 21-31-03-400-801. GROUND TEST ACCOMPLISHED, ALSO PERFORMED PRESSURIZATION TEST AND VERIFIED RATE OF CLIMB INDICATOR WORKS NORMAL AMM 05-51-91-790-801.