What was found
AT JFK FLT 77, EXPERIENCED BRAKE ECAM ON T/O ROLL AT LOW SPEED. ABORTED T/O AND RETURNED TO GATE. T/S FOUND NR 1 TACH SPLINE DAMAGED & HUB CAP, ALSO NR 3 HUB CAP SPLINE FAN TACH. REMOVED AND REPLACED NR 1 TACH, NR 1 HUB CAP AND NR 3 HUB CAP PER AMM 32-42-68, 32-38-51, PERFORMED OPS CHECK PER AMM 32-42-00, SYSTEM OPS CHECK GOOD.