I have exactly the same problem as bl_twisted_st. I couldn't have described it better. If you find the source of that maddening clank PLEASE post or let me know some other way!!! I promise I'll do the same. I have been searching for this clank for months. I spent a lot of time on the floor while my wife clanks, trying to pinpoint its location. To me, it does not sound like it comes from the back. It sounds like it comes from the point in the middle near where the left foot is at its lowest position, but what could possibly clank there? Still, as I move my ear to either side of that point it seems clear that the clank is there. Any ideas? I have the 10 year warranty, but (after a previous experience with him) I have little faith that a return visit from the authorized repair guy will be productive. I can usually fix this sort of thing myself, but I'm stumped (so far). The clank is driving me crazy, ruining my exercise experience, and I am obsessed with finding it. HELP!!!