Unplug the dishwasher and open the front door. Remove the bottom wash rack and set it aside.
Locate the spray arm inside the dishwasher. Use a flat-head screwdriver to remove the screw that holds it in place. The spray arm is located in the center of the dishwasher. Remove the spray arm and set it aside. If the dishwasher has two spray arms, remove both of the arms.
Remove the spray arm support and locate the impeller behind it. Using a small, flat-head screwdriver, pry the old tub gasket off and replace it. Purchase a replacement gasket for an authorized Electrolux service center.