Infinite vertical scrolling menu

I am using POMs tutorial for making an infinite menu
This one is vertical instead of horizontal.
The MC is 1696 pixels in height. registration is top middle
i drag 2 of these MC’s so one is below the other (total height 3392)
Here is my code


onClipEvent (load)
onClipEvent (enterFrame)

   var distance=_root._ymouse-ycenter;
 if (_y > 0) _y=-1696;
   if (_y < -1696) _y=0;

The clip goes really fast and is making me foam at the mouth if i look at it for too long!
I tried changing ycenter to 300, and it is much smoother but it is very jumpy when moving back to the position determined by the code.
Any help is great