My wife told me the light was out in the clothes dryer drum so I removed the screw holding the awkward to get to clear cover to the light compartment, removed the 10 watt bulb and headed to the HD. But all they had were 6 watt bulb-s- which I knew she would be telling me wasn't bright enough.
I hit another HD and then a Lowes-- where I confirmed the existence of The Great Zero Inventory 10 Watt Dryer Drum Bulb Shortage.
I came home empty-handed and was about to tell her to just use the dryer as it was until I could find a bulb. But then I noticed the first actually useful product warning label I've ever seen: "Do Not Operate Dryer Without Bulb and Cover."
No doubt to keep humidity leading to a short or corrosion out of the bulb socket.
So I screwed the bulb back in and hey, the light comes on! I'm thinking eight years of drying clothes subjected the bulb to enough vibration to back it out.
Lesson learned? Before you remove/replace an appliance bulb that ain't coming on, make sure it's tight!