Actually force feedback is purely to do with rumble im fairly certain
because they sell ordinary controllers with the "force feedback" buyline and they aren't steering wheels :P
the centering is to do with how the steering wheel works electronically, you know how ps2 joysticks have 2 pots on them? Well the steering wheel has one of the pots, the X/horizontal axis, and thus, like a steering wheel and a ps2 joystick it flicks back into the centre
now im starting to waffle instead of helping GAH! Chances are if you've been doing some serious racing one of the wires may have come loose on one of teh rumble motors, there will be a positive and negative wire for each motor, there is usually two, just solder whichever one back where it belongs
hope that helps
