I have an apache AH-64

these are my problems:
My bottom (B)blades doesn't spin sometime, like when in good flight the bottom blade stop spin and turns so crazy and crash to the ground...
now I open it... there's a new problem
the top motor which spin (A) blades, it keep making cracking sound when it spin, but when the motor and the rotor (not sure what it's call the circle think that connects to the motor or engine) separate, it goes smoothly but when it's connect it makes cracking sound so please help me