What was found
BRAKES INEFFECTIVE DURING LANDING ROLLOUT WITH LIGHT TO MODERATE PRESSURE. WILL GRAB WITH HEAVY PRESSURE. SAME ON TAXI, INEFFECTIVE WITH LIGHT TO MODERATE PRESSURE. REQUIRES HEAVY PRESSURE FOR BRAKING. REMOVED FROM SERVICE. DURING FUNCTIONAL TEST IAW AMM 32-42-00-720-801, NOTED THE NR 4 BRAKE PRESSURE DID NOT REMAIN AT 3000 PSI, BUT BLED OFF TO LESS THAN 2000 PSI AND REMAINED THERE AND RESERVOIR QUANTITIES CHANGED. REMOVED AND REPLACED THE NR 4 BRAKE FUSE, SHUTTLE VALVE ASSY IAW AMM 32-42-11-000-801, AND 32-42-11-400-801. FUNCTIONAL CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.