I've received my Phantom and carefully balanced all the props, two needed a little work. Before I mounted them I started up the motors and was dismayed to find how much the Phantom shook even at low throttle. It smoothed out a little as I increased the revs, but still fizzed as I held it. There's nothing loose in the motor mounts, and the motors did not come with labels on. Is this expected behaviour, and will I be wasting my time trying to get perfect balance on my props?