Definately ballance the fan, but don't try to ballance the clutch as it is almost impossible because of the threaded interior and the shoes that move in and out as it works. Definately ballance the blades, tail rotor blades (best done as a unit like an airplane prop), and the flybar on the rotor head before you install the blades. Most all of the ballancers work well, so IMHO it's a personal choice.
Also, if you already have it flying, blade tracking can cause vibrations and I've even seen it when the blades "apeared" to be in track. You might change the tracking a little one way or the other to see if the vibrations gets better or worse.
Good luck with your Hawk.
The government cannot give you anything without first taking it from someone else.