Hi Linda, if you would like professional advice find me via microwave-repairs.co.uk we are factory trained and approved by all major manufacturers.
kindest regards
patrick
July 2009
They sensibly don't like the users messing around inside microwaves for safety reasons - we are expected to have a trained person change the lamp.
Access is from the outside - you need to take the covers off but be sure you've pulled the plug and don't put it back in until the machine is all properly reassembled.