As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ROLLING TAKEOFF, ADVANCED THRUST LEVERS NR 2 WENT RIGHTUP TO 50 % NR 1 HAD A 2-3 SECOND DELAY. WE DISCONTINUED TAKEOFF. ON SECOND ATTEMPT WE DID A STATIC TAKEOFF. SAME RESULT. ONCE ENGINES STABILIZED THRUST WAS ADVANCED AND NO FURTHER LAG NOTED. LAG WAS FROM INITIAL THRUST SETTING 50% UNTIL STABILIZED. ADVANCING TOFLEX NO LAG NOTED. ACCOMPLISHED POWER ASSURANCE CHECK ON BOTH ENGINESS AND ACCEL CHECK IAW AMM 71-00-00. FOUND BOTH ENGINES TO BE WITHIN LIMITS. OKFOR SERVICE