Do the following:-
1. Turn the power off (on the main wall switch).
2. You now have to pull the oven part way out from the kitchen unit (about 6 inches - but be careful, it is heavy).
3. Then remove the 4 little screws that hold the top bezel in place.
4. Remove the top bezel by lifting at the back and pulling forwards.
5. Now remove all the control knobs and buttons by pulling them off.
6. Then the glass panel can be removed by pulling towards you at the top until it clears the control shafts and then lift it out of the bottom channel.
7. You will see the fluorescent tube across the bottom of the control panel. It is removed by applying a little pressure at both ends (only to the metal caps, not the glass) behind the tube and rotating it (it must turn 90 degrees to release and then pull it out towards you).
8. Replace the tube by pushing it in and applying pressure at both ends until it locks into place.
Then reverse all the steps above. It is possible that the fluorescent starter or transformer is faulty rather than the bulb. These are accessed from under the top panels - but ask again if you need advice on that.
T Fixit, March 2009