The K45 is almost 50 years old and is still a workhorse. The locking base is easy to replace, it is held in place with 3 screws. Remove the screws, and a small amount of tapping and the base popped out, even after being in place for so long. The new base is slightly different. There is a rim around the opening and the old base fit inside the rim. The new base sits over the rim. I lined up the base to match the screws and laid it in place. Again a small amount of tapping and it snapped into place. Put the screw back and it was ready to go. $13, parts and shipping versus $200 for a new unit.