You may need to simply clean the contacts on the Camera and the Mounting plate. I will give a link that has more detail and suggestions to try if you are NOT loosing video completely .|
As far as the motors reducing speed , that is a normal warning that is pretty much benign. The AC moving up and down is pretty normal behavior with my aircraft, I notice it as well and just consider it part of the flight transition , I dont think it is anything to worry about , make sure that you dont have excessive play in the landing gear as if it was to get considerably sloppy it could give some poor flight performance during transition , just feel the gear for excessive slop and check the support rods etc.
I agree the phantom does hover better . One thing to be sure to calibrate would be the IMU and also do a good compass calibration , see if it helps . I think you may have already done this but just wanted to mention it as well .
What are you using for go app. , you need a fast processor for the Go app , I know I harp on this a lot but if you can get a I pad Pro or Air with plenty of memory your issues may go away not sure . When you get the weak transmission on the go app do the HD bars drop as well ? If they do NOT, I would look to your go app device as the culprit .
also if you can , try to use channel 20 on the image transmission settings, it has NO wi fi competition ( some wifi does overlap , but it is a very quiet channel )
Check this link out .
https://docs.google.com/spreadsh ... li=1#gid=1477125990
If the screen turns funny colors like green etc with lines then It would be the camera , any way , look over my tips page on this and let me know what go app device you have .
Video Transmission issues with X3 or X5 ? Try These Suggestions !
Hope this helps, I personally dont think you need to send it in at this time .