I saw a dealer using an aluminum bar with two pins (thats what I call them. The pins fit into the cam on mathews bows. He states that even though they say that single cams cant get out of tune they are wrong. I think he may be looking to see if the bar aligns with the string or cable?? He says if it doesn't line up he can twist the string to get it to realign. Maybe I am way off here, wasn't really paying too much attention.