Help! My Phantom has been flying fine but suddenly it seems to have only a fraction of its normal power at start-up. My partner is holding the PV2+ (high over his head) so we can "feel" what is happening. We can tell, just from the sound, that if he were to let go the unit would fall to the ground since there is so little power. There doesn't seem to be any imbalance in the rotors, all of which are spinning fine. Even when I throttle to send the PV2 up, there is no noticeable increase in power. However, when I move the left stick to the 5 o'clock position, we can hear a definite increase in power, but the unit strongly pulls down towards the left. I ran in through the Assistant, reset gain to default, calibrated, etc. No change. I bought this unit from DJI and had it shipped from Hong Kong. It's flown about 6-8 times with no problem, but I just shipped it and can only wonder if something went awry during shipping. Does anyone have any suggestions as to what I might troubleshoot before I send it back? Thanks!