Hi Rob, I finally got out to the hangar to take a look at my problem. I may be missing something though in the calibration menu, I cannot see anything detailed as 'NVRAM defaults'. For clarity I have the non 'S' type 3400 EFIS's so hoping you could still point me in the right direction to remedy the issue. I have two screens and one screen has the wind ok and the other screen although it clearly has GPS information fed to it from my GPSMAP-495, the wind calculation is blank on the screen. As always appreciate your expertise and advice. Cheers, Greg