I've had three old world slings since I've come into the hobby in the last month. All my slings do this to some extent. My Obt was the worst about it too. Wouldn't even see it eat, but out of the corner of my eye I noticed something. That's where the thrill comes for me. Those brief moments when you do see something.Just got a Brazilian white knee sling I have not seen him since he borrowed it's only been a day and a half I'm pretty sure that's normal I just wanted to see if anybody else had anything to say it's my first sling