Danny,

If you are still getting significant movement on your string loop after 1000+ shots then it would lead me to believe that you are either shooting a bow with the older fastflight string material installed (which shouldn't be the case provided the bow you mentioned has the original string/cable on it) or the string loop is moving. Now, you did state that you didn't believe it was the string loop but I would ask you how you know that it isn't? Did you mark the string both above and below the loop knots to use as a baseline to judge movement? If you haven't then try it and see what happens.

Something else to consider is that maybe your center serving is moving and not the string or the string loop itself.

Straightarrow,

I was trying to visualize it for awhile too and I kept coming back to the image of a rubber band. Imagine stretching a rubber band over a door knob. As the rb is stretched the material "moves toward" the point where the most pressure is being applied. In the case of the rubber band that would be the door knob. In the case of the bowstring it would be the idler wheel...unless I am missing something here.