What was found
AFTER TOUCH DOWN, THE BRAKES LOCKED UP ON TAXIWAY, AIRCRAFT UNABLE TO TAXI TO GATE, SHUTDOWN AND DISEMBARKED PASSENGERS ON TAXIWAY. MAINTENANCE REMOVED AND REPLACED PARKING BRAKE SELECTOR VALVE IAW AMM 32-45-51, LEAK AND OPERATIONAL CHECKS WERE GOOD. CONFIRMED FAILURE OF UNIT FINDING ONE SIDE OF THE MOTOR WAS INOPERATIVE AND FLUID LEAKAGE AT RETURN PORT VALVES. REPLACED MOTOR AND SEALS AND RE-ACCOMPLISHED FUNCTIONAL TEST IAW CMM 32-47-24, REV. 4.