Remove the blade guard by undoing the two thumbscrews located behind the blade. Loosen the screws then lift the blade guard up and off the machine. Set the guard aside for later.
Remove the large nut in the center of the blade. The top of the nut is about 1 inch across with a hexagon shape. Set the top of the punch against one corner of the nut and tap on the punch. This will help to cause the nut to begin unscrewing. When the nut is loosened you can completely remove it with your hands. Using the punch lessens the chance of cutting your hands on the blade.
Open the slicer to the widest aperture by turning the slice dial to the largest number. Put on work gloves and carefully remove the blade from the slicer body. Place the slicer blade in a safe container like a cardboard box to keep the sharp edges away from people.
Clean the body of the slicer and blade guard thoroughly using regular dish soap and a sponge or dish scrubber. This is the only opportunity you will have to clean certain portions of your slicer. Allow your machine to dry thoroughly before proceeding.
Use work gloves to grasp the new blade and slip it onto the spindle, replacing the old blade. Place the nut onto the center of the blade and tighten it with your fingers. Finish tightening the nut by reversing the process with the punch, tapping the edge in the opposite direction. Replace the blade guard to finish your installation.