Not easy, you have to remove the top cover which is scured with about 7 screws at the rear side and base. Thing is althouh 6 are straightforward 1 will proberbly be a special socket no doubt due to mircowave regs. Anyway once removed there is a label "20w SES 230v" this identifies where the bulb is. There are 2 lugs which need to be bent upwards to allow remove of the lamp holder. Then its just a case of refitting all the bits, ensure the lugs are located when refitting the cover. Goes without saying to disconect mains before doing any of this. Good luck.
John Boy
January 2008