An alternative would be to reset the calibration.
Unplug the controller, click Start>Run, type regedit and click OK. In the Registry Editor browse to the following folders in order:
HKEY_LOCAL_MACHINE
SYSTEM
CurrentControlSet
Control
MediaProperties
PrivateProperties
DirectInput
And delete the VID_06A3&PID_0255 folder. Plug the controller back in, rotate and twist the stick fully a couple of times and see if that has fixed it.
This is from Seitek support, read all about it at:
http://www.saitekforum.com/showthread.php?t=9779