Be advised that on whistle motors the impeller inside the resonance chamber is pressed on the shaft. As such the armature cannot be removed from the motor and the lower bearing cannot be easily accessed. It is still important that the lower bearing be lubricated as it is the one that more often goes bad, at least in my experience. A needle oiler is helpful in this case. Also be careful removing the brush plate cover as Lionel often does not leave as much lead from the field coil as they do on drive motors. It is sometimes better to unsolder the wire to the field coil rather than try to flex it.