I need to replace light on kenmore microwave oven model 721.66312

I Agee with Ray - You can gain access to the lamp holder by removing the outter wrapper - unplug the power before you start

unplug microwave and remove old bulb for size and wattage. it should be easy to access.

Unfortunately,you are describing a microwave that has died.

To replace the light go to the link below page 29.

http://www.managemylife.com/mmh/owner_manuals/21573/KENMORE-Microwave-Hood-Combo-L0310077?brand_name_search=721+63664300

You may have to get your spares through Kenmore.com

http://www.managemylife.com/mmh/owner_manuals/11148/
KENMORE-Microwave-Hood-Combo-L0310032?brand_name_search=62649200

go to www.applaincepartspro.com and you can order anything you need from there and are fast at shipping.

Usually, when your microwave oven doesn't work it all, the internal fuse (thermal fuse) is blown. This fuse protects both you and the oven. When it blows, you need to have a qualified appliance repair technician replace it.

Door switch If the fuse isn't the problem, check the door hooks and the door-release button. When these are broken, the door switch doesn't activate, so the oven can't work.

Unplug the unit first.

To install the halogen lamp WB08X10050 you will need to take the cover off. You can see a diagram at;
http://www.searspartsdirect.com/partsdirect/getSubComp.pd?modelNumber=36363693302&productCategoryId=0123370&brandId=0583&modelName=MICROWAVE&diagramPageId=00006&componentDescription=INTERIOR%20PARTS%20(2)&documentId=S9060341&backToLink=Return%20to%20Sub%20Components%20list

then click on "view full size"

This will give a view of the parts. Only remove the parts needed to get to the bulb.

The problem is likely on the control panel, which we repair nationwide for $39.95 postpaid.

This light failure often occurs when a bulb goes out and the filament shorts, or when the bulbs are removed or installed without first unplugging the oven from the power line. Either can cause such a failure on the controller.

This often can affect the exhaust fan operation, too. The lights and fan can be inopoerable or stuck on.

If you or a friend decide to look into it, we have critical safety information, info on door switch diagnosis and replacement, and

disassembly information at our site, linked here on Fixya: http://tinyurl.com/yzjozk