If one or more of your axes are only displaying 1-99% and you have tried to set the sensitivity to max and the nullzone to 0 then this is the fix.
1. You will need to edit the values in a text document inside the FSX folders
2. To navigate to this:
C:\Users\yourname\AppData\Roaming\Microsoft\FSX\Controls
where yourname is usually the account name you are logged on as.
To see some of these folders you might need to show hidden folders.
3. There is a single XML document in the Controls Folder. You can open this with Word
4. Almost near the bottom you are looking for < SimControls.map >
5. Then you need to look for the device that is causing the problem, for example< Name >Pro Flight TPM System SLEW {C60814B0-F7D4-11DF-8001-444553540000}< /Name >
6. Then you need to look for the < axis > to ammend. For example the throttle has a 1% null zone: < AxName >RzAxis< /AxName > (The axis name for your controller might be different, the throttle could be Z also)
7. Looking in this subsection you will see < AxNull >1< /AxNull > This 1 is causing the problem so change it to a 0 to look like this: < AxNull >0< /AxNull >
This will fix any nullzone issue. Once you are happy with the changes save the Standard.XML so the changes will take effect.
You can then re-run FSX
Technical support telephone numbers can be found here