One little niggle with my daughters car is the steering wheel 'leather' has gone all lumpy at the top and you get black bits on your hands when driving it. Want to change it. Do I have to disconnect the battery when taking the air bag out and do i need a puller for removing the wheel, or just undo the nut ( and not remove it !!) and just bash under the wheel to knock it off the splines ? Also anyone have a good nick wheel I could buy? Cheers.