As soon as you receive your Gaskets/Seals take them out of the box. Due to the nature of plastic they are likely to have some kinks.
Lay them out in a room that is of normal temperature. After about 30 minutes they should be ready to fit.
Always push/retain each corner in place first before working to the centre of each side. This is especially important with longer Gasket/Seals as the weight of the seal can stretch the Gasket/Seal and make it appear too long. For a visual demonstration please Click to see: How to Replace a Dart Fixing Gasket/Seal.
The Gasket/Seal can only work correctly if the door and the frame are flush and the appliance is reasonably level. If they are then the Seal created should be fine.
Sometimes the magnetic strength of the Gasket/Seal can feel a little weak, this is quite common and the full strength is not usually achieved for about a week.
It is also possible that the profile of the Gasket/Seal has squashed slightly, this can mean that certain sections of the Gasket/Seal are not touching. You can use a hairdryer to apply some heat to these areas which swells the profile back to its original shape (Caution: Do not heat for too long or hold the dryer too close). For a visual demonstration please Click to see: Tips on How to Achieve a Perfect Seal.