My PV has been working great and stayed calibrated for a while but now I'll calibrate the compass and fly fine, but when I put it away, get it out another day and fly it isn't calibrated anymore. I'm storing/flying in the exact same way in the exact sale place. Not sure why it now won't hold calibration. I thought the compass may have gone bad but figured it wouldn't calibrate at all if so. It calibrates but won't keep. Perplexing.