I have just had the same problem. You will need to buy a tube of heat resistant silicon sealer which you can get online or at your local electrical repair supplier. The stuff I got is called HEAT MATE. You will also need a standard sealer gun to apply it.
Take the oven door off. To do this open the door and look on the top of the hinges where they fit into the front of the oven you will see a piece of metal folded over the hinge which is fixed at one end. This swings upwards you will need a screwdriver or pliers to lift it. Do the same on both hinges then close the door a little bit and the hinges will move allowing you to lift the door clear of the oven.
Look at the bottom of the door the hinges are fixed with two screws each, these also hold the inner skin to the bottom of the door. Unscrew these screws and the bottom of the door should separate. The top of the door is glued inside and I could not separate it completely so be carefull I just opened the two halves as far as I dare and wedged them apart and worked through the gap. Remove the inner glass and clean it. Clean the oven door inner skin and remove the old adhesive, for the new sealer to stick everything needs to be clean, dry and grease free.
Next lay the cleaned glass on a flat surface and apply a thick bead of sealer onto the face of the glass at the outer edge where it will be in contact with the door. The oven door needs to be face up with the window opening facing downwards it might be better to get somebody to hold it up so that you can pass the glass through the gap into the inside of the door and lower it into position. You may need to get your hand through the window opening to support the glass as you lower it into position. Press it down firmly to make sure the sealer is in contact all the way around. Some sealer will squash out but this can be cut off with a sharp knife when it has set. Put the door somwhere flat and leave overnight for the sealer to set.
Fasten the hinges and the inner skin back together and re-fit the door pressing back down the little clips that you had to lift up to get the door off. Leave the oven for 24 hours before using it to make sure the sealer has set.
Happy cooking
Bob
December 2008