Edited 5 - This issue has been merged with the below link
Hi…thanks again for the feedback…I checked the motors individually using the motor slider QGC menu and all have enough power to single handedly tilt the 2.5 KG weight drone to one side !!! ( In fact during my last trial , one of them ripped opened the stator cover of the ESC motor while hitting the ground during the slider test 
) So I am assuming there was enough power from these motors. ESC calibration was done many times directly thro USB -PC interface with QGC ( on pc side) …
What does this parameter " gnd-speed_thr_sc " do as far as lift goes . i see that increasing the value , increases the throttle during lift…