Fisrt of all you need to remove the oven door. This is done by lift the tabs on the two hinges (the tabs are the same colour as the hinges and you will need a flat blade screwdriver to lift them up. Once you have done this this the door should them come out of its locations. You can then move the front glass part which can be done by sliding it to the left or the right. You should then have access to the glass.
lee, October 2009