Phantom won't take off

[video_ehouse]

Hi, I've recently added the gimbal to my Phantom, and that works all ok. However, it seems like the 2 front motors aren't spinning as fast as they should. Even when I do the motor test on the assistant software - the 2 front propellers don't spin as fast as the rear ones. So whenever I try and take off, the Phantom just nose dives. Can anyone help, please?

 

[Gizmo3000]

Have you tried pulling back a little bit on the right stick while taking off? (so as to give the front motors a bit more throttle)