Never had to replace a controller...
However, I am having a problem with one of my PS3 launch controllers. The left analog stick is... sticky. It doesn't want to return to "neutral" and it won't register fine, steady motion properly (like on a radial menu).
It makes certain games really difficult to play (Mass Effect 2, Dragon Age O or 2, Assassins Creed 2/Brotherhood).
Also, this same controller will occasionally turn itself off (while still having plenty of power left).
My other launch controller is fine (I got 2)... this one is just off somehow. It still works, but it's a pain, and I've been considering buying a new one and retiring this one.
Anyone else had a problem like this with their PS3 controller?