Remove screws on side and back of microwave. Slide outer casing back and remove it. There are two terminals on top of the light globe which are connected to some wires by a small plastic connector. Unplug the light globe by pulling on the plastic connector. Moving aside any obstructing wires carefully remove the old light globe and replace it with the new one making sure the terminals on top of the light globe are facing toward the connecting wires Plug the terminals on top of the light globe into the connector attached to the wires pushing firmly to make sure they go all the way in. Replace the outer cover by placing it over the microwave and sliding it forward so the top and sides are a snug fit. Replace the screws.
Tip the nuke upside down (after removing glass table and roller support), remove the appropriate screws, lift panel (disconnect the short earth connector), remove panel, unscrew motor cover and replace motor. Reassembly is reverse of removal (where have I seen that before)