Sent my fc40 to dronenerds for repair, motors were chattering due my stupidity on too long of screws when removing prop guards. Bought new anti gravity motors from T motor and sent them in with the drone. They needed to also replace 2 speed controllers. Got it back with assurance it had all been tested and worked fine. Not quite, the gps in not functioning at all. It worked prior to sending in, there response is we, we don't have any gps units. It is difficult to fly without gps and looking for a repair facility that can look at it. Thanks, Eric.