My Phantom is calibrated within limits. .4-5 average for the third value in software assistant. I have seen it hover really well. The last two flights, I launch it hovers well for about 5 seconds then flies a small circular pattern that gets bigger and bigger. I have to fight it to maintain control. This is a compass problem right? If it is, the compass is that DJI provides is the best one use for a compass calibration?