You can get serving in several different sizes, from .014 - .030, for example. My normal serving is .021. If your nocks almost fit, just go up to the next larger size. If they are quite loose, consider double serving. Serve 2-3” in the nocking area with small size serving, then serve over it with a larger size serving, wrapped in the opposite direction. Or, if you would like extra cushioning for your fingers, extend the double serving to cover the area where your fingers hold the string as well.