The joystick will occasionally send ridiculously high resistance readings, which will
screw-up the calibration. Try any generic electrical cleaner (contact cleaner works best, try to avoid cleaners with heavy lubricants).
BTW - Got a Thrustmaster T-1 - FANTASTIC! How many people like the "pedals"? I'm still using my MAXX pedals because I like to drive in my socks! Anyone rig up solid pedals on the T-1 base?