Always replace the cotter pin. Make sure the inner bearing race is seated all the way. One way to ensure proper seating is to tighten the bearing down hard with the axle nut, loosed to where you can turn the drum, turn and redo that a few times. there is no Ft/lb spec for the wheel bearings. The manual just says to tighten until you can barely move the washer under the nut by prying with a screw driver. My measurement of the net result of that is about 30 ft/lbs which is a bit tight in my eyes.