Open 360 controller?

How can you open the 360 controller? It has star (torx) screws but my torx drivers don't work because there is a little thing pointing out in the middle of the screw... Can you even buy those in stores?

If you are wondering why I need to open it, it's to repair it because the thumbstick is loose..

it voids the warranty if you open your controller, i thinkKickinurazz

I'm sure it does, since you have to make a hole in the bar code.