As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT LEFT BRAKES WERE PULSATING & GRABBING. CREW OBSERVED YELLOW ACCUMULATOR PSI LEFT NEEDLE GOING TO 400 PSI ON ITS OWN AND RELEASING-WITH ASSOCIATED GRABBING FELT. REMOVED AND REPLACED LEFT NORMAL BRAKE SERVO VALVE IAW AMM. OPS AND LEAK CHECK GOOD. REMOVED AND REPLACED NORMAL SERVO VALVE IAW AMM, OPS AND LEAK CHECK GOOD.