If you thought it couldn't get worse with Proform, try the 520 ZN. Cheap motor, oversized belt = repairs.
Although they sell this machine and it looks great, the bad of this machine is that when it breaks down, you will look at it and say?what an expensive looking treadmill. I think I will repair it rather than getting a new one. Then you will think the same thing six months later, then again in another six months and before you know it, you will have spent nearly as much on repairs as you would have spent if you bought a treadmill for twice the price!