As far as your suspension not returning, it has more to do with the springs on the side than the shocks. Make sure they are under tension and adjusted properly. Also I would bet that if you lift the back of the machine off the ground, the straps will be under pressure (it is normal for slack when the machine is sitting on flat ground). If you get your spring issue under control so that the suspension rebound is correct for your weight, I wouldn't be suprised if your noise would go away. That and make sure your track tension is somewhat close to spec