Remove all the laundry and water from the Whirlpool Duet washing machine. Unplug the unit from the wall, disconnecting it from the power source.
Open the door of the washing machine. Unscrew the three screws that hold it in place. Remove the door and set it aside with the screws.
Examine the gasket carefully for tears or rips. If you don't find any, your gasket may only need a good cleaning. Wipe it with a cloth that has been dipped in a solution of bleach and water: 3/4 cup bleach to 1 gallon of water. Clean the seal completely with the solution.
Remove the gasket by prying it from the rim of the washing machine using a flat head screwdriver. Pry the gasket on each side, then pull it off the washing machine. Wipe down the edge of the washing machine using the cloth dampened with bleach and water, removing residue and grime. Allow the edge to dry before replacing the gasket.
Slip the gasket or boot out from any hoses connected to it. Replace the gasket, returning the hoses to their original position. Use the screwdriver to help you maneuver the gasket back into place.
Return the door to the front of the machine and screw it in place. Test the seal on the door by running a small load of water.