How do I replace a light bulb in a Frigidaire model MC-850M microwave?

My mom has a really old Frigidaire Touch 'n Cook (model # MC-850M) microwave. The light has gone out. The manual says to contact a certified Frigidaire technician. I'm sure I'd be able to replace the bulb, but am not sure of the proper parts to remove to access it. Can anyone help me?

Thanks!

Nancy