The axle to axle can change when BOTH the string and cables stretch.My brother has a Defender,and is shooting it with a Trophy Ridge Drop Zone rest.He hasn't had any problems with tearing tail left,or tail right,He had trouble with point high tears,he solved this problem with cutting his arrow length down,this making his arrow stiffer.He is shooting a bullet hole with his Defender now.Make sure you have center shot before you try anything else.After setting center shot to center,then try different spined arrows.You might have to buy different arrows for this bow compaired to your old bow.Just because the arrow chart says this or that arrow,don't mean there is something wrong with your bow because it won't tune that particular arrow.With the Binary cams,they WILL stay in time,even if your string and cables stretch,thats what they are suppose to do.Hope this helps,if you cannot get the bow to tune,then take the bow to a good proshop,they should be able to find an arrow that will tune and shoot.