Try this. Drive the car in a straight line and get it to where it goes straight. Then crank the steering to one side and then let it center again. If the car steers in one direction or the other, you either have some slop in your servo saver or possibly a broken tooth on one of the gears in the servo. It's also possible that the servo saver is moving, but there is too much resistance in it to recenter again. I hope that helps