My mini model master sky copter will not take off

Question

My heli copter will not take off it rises a few cm off the ground and it spins it is not a trimming problem it seems to have some sort of resistince on the main shaft and it viabrates it is like the resistince is slowing down the rps so that it dosent have enough power to take off. it is not a problem with the rotors i have made sure. my model is made of styrofoam and can not be opened is there any way i can fix my chopper i really love it !