As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER COLD SOAK AT ALTITUDE, BRAKES VERY GRABBY. PEDAL DEFLECTION OPERATES NORMALLY BUT NO BRAKE PRESSURE ON INDICATOR APPEARS UNTIL AN INCH OR MORE BRAKE PEDAL DEFLECTION. THEN THE BRAKE PRESSURE JUMPS TO 600 PSI AND THE BRAKES GRAB AND JERK THE AIRCRAFT. REMOVED FAILED ANTISKID CONTROL UNIT, AND INSTALLED A TESTED UNIT. NO DEFECTS NOTED.