Hi It's quite easy really. Unplug microwave. Unscrew the screw at the side of the microwave and the outside screws around the back of the casing. lift off the casing ( you may have to wiggle it a bit but it will come off. You will see the bulb immediately. Unscrew the bulb. You will need 25w Xbm 240-250v Heavy duty bulb. Reverse the above and put Microwave cover back. Finished.