In my non expert opinion cam lean is the right or left lean on your cams as if you were looking at it from the back of your bow in a vertical position. To cure this problem on split bus cable bow you need to twist one side of the Y to offset the lean.The part where it splits into smaller cables about 4 inches from the end. You must also have (not sure of the technical term) a cable that doesnt float at the Y. I dont think there is much you can do on single cam bows but i am not for sure.