Inspect the cabinet leveler and adjustable wheels. Place a torpedo level on top of the refrigerator and make sure it is level. If not, adjust the levelers or wheel underneath the unit.
Move the leveler or wheel up or down by using a wrench to rotate the adjustment nut. Once the refrigerator is level, the door should seal all the way around.
Open the refrigerator door, and loosen the inner panel mounting screws using a socket wrench or nut driver. Loosen from the top, bottom and handle side but not from the hinge side of the door. Do not remove the screws.
Hold the toe-in side of the door stationary while pushing down on the toe-out corner of the door. Close the door, and check the seal.
Tighten the screws back down when the inner door is aligned square with the cabinet.
Purchase a door seal for your refrigerator at an appliance repair shop if the previous steps did not correct the problem. Be sure to have the refrigerator brand and model number with you when requesting the gasket.
Fill the kitchen sink with warm water, and place the new gasket in the sink. This will make the new gasket easier to work with when installing.
Remove everything from inside the refrigerator door.
Loosen, but do not remove, the inner door retaining screws located behind the gasket.
Pull the old gasket away from underneath the metal retainer and off of the door. Install the new gasket underneath the metal retainer starting at the bottom of the door.