Another thing it could be is the radio.
if its a cheap radio that came with the heli then I could be barking up the wrong tree.
However, if the radio is a more expensive one then the gyro mode within the program might be in the wrong setting.
I say this because I had this experience a while back, basically I had been messing with the radio and a sim...I had switched gyro modes from 'GY' to 'normal'...the normal being for the older type gyro...so the gyro was there but couldnt work...I still had left and right control overall...but the gyro couldnt compensate.
I flew the heli quite well but on hovering it was very unpredictable...and ended up on its side with a set of new carbon blades getting totalled in the process
Rob