I had the same problem when I had an X-52 Pro. I cured my problem by buying a CH Stick. Kidding aside, I found at times when I lost calibration in game, you can simply unplug your stick, wait about 10 seconds and plug it in again.
You can do this in game, but make sure you put your auto pilot on. For some reason that would reset the calibration. I have no idea why, I simply found this out by accident. Mine was plugged into a powered hub. I don't know if this would work if its not.
Throwing an option out there.
Fred