Set up the grinder attachment with the coarse plate. Working over a large bowl, gently press the meat through the grinder. Clean the grinder, then set it up again with the stuffing tube attachment (this time, without the blade and coarse grinding plate). Lightly grease the stuffing tube. Slide the casing on the stuffing tube, leaving about 2 inches of overhang. With the mixer on low speed, pass a handful of meat through the machine. Once the sausage begins to collect in the casing, form the sausage with your hands and tie the end of the casing in a knot. Increase the speed and pass the remaining meat through the stuffing tube, holding the sausage loosely in one hand to control how tightly the sausage is packed.