There is an access / cover panel on the back of the oven.

It's shown in the exploded view here.

Please unplug the oven from the wall first.

Then use a 1/4" nut driver or socket to remove the screw in the end of the lamp cover.

The bulb is behind the cover, and should be readily available at grocery stores, home improvement centers, hardware stores and big box stores like Wal-Mart.

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