Disconnect both servos and then operate them to the limits desired. Are they quiet? If so the problem is in the aileron/linkage. Perhaps you are simply trying to get too much deflection and binding at the extreme end. It is important to try to get close to the recommended throws by adjusting the linkages first and using the TX computer last. When linkage is set for recommended throws at ailerons, do they "buzz"? If so, find the bind and fix it.