i have a fc40 was flying and crashed to the ground had to replace the case and the motor was ripped off so i up graded the motors got it flying hoovers but while its hovering  like drifts away dosnt hover in one spot took it to a hobby shop they couldnt figure it out also sometimes if im flying it like just takes off i cant control it at all just flys away any ideas need help http://youtu.be/ZiKJ0y8i-Vg the link to the crash

Right from the beginning of that flight the motors didn't seem to have a smooth buzz I'm accustomed to -- I hope the replacements sound better.

Have you tried a complete new set of props to see if it affects the drift (you'd be surprised what one funky prop can do)

Are you getting the normal LED indications for Home Point set and GPS lock?

When you fire up the DJI NAZAM Assistant software are there any obvious problems, are all the IMU settings within normal limits?

well this is what I got

gil Posted at 2015-1-19 20:42
Right from the beginning of that flight the motors didn't seem to have a smooth buzz I'm accustomed  ...

I posted two pictures on what I go going on

ryank1870.email Posted at 2015-1-22 04:45
I posted two pictures on what I go going on

Dang, dude -- got a stiff neck trying to look at those photos sideway!  
Your compass MOD is way, WAY out of spec!   It shows 6677.1 when it's supposed to be between 750 and 2250!  Follow the directions as shown on the screen capture from my first reply to demagnetize the compass and try again.  

This is also in the user manual and I highly recommend you download a copy, print it out and have it in a binder for ready reference!