I've been having a problem with my Nordic Track Achiever and I was hoping someone might have a suggestion as to what I might do about it. This is a refurbished unit I bought about 2 years ago. A couple of months ago we noticed that rubber was coming off the drive rollers (one, in particular, was quite bad). I thought it was the rollers so I got replacements. But now I'm beginning to see the same thing happening again, with one of them particularly problematic. So I figure it must be the skies. And they are pretty worn where they contact the rollers. Is there anything you can do with the bottom of the skies to prevent them from ruining the drive rollers so quickly?