As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHILE STARTING ENG NR 1, PARKING BRAKE WOULD NOT SET. FOOT BRAKES WERE FINE, JUST PARK BRAKE HANDLE WOULD NOT SET UNTIL ENG NR 1 FULLY STARTED. CARRIED OUT OPERATIONAL TEST AS PER AMM. CONFIRMED NO POWERFROM 'NORMAL' SOURCE. REPLACED PARK BRAKE CONTROL VALVE-NIL FIX. REPLACED PARK BRAKE SELECTOR SWITCH-OPS CHK'D SERV.