I've done it before, just not with the headlight off my bike. 300deg F for about 10 minutes should be enough. Don't forget to wear oven mits!! Just keep an eye on it and check it a few times during the "baking" to see how its doing. The other option would be a heat gun or hair dryer.
I've done it with my bike headlights before. Like xtreme said, about 300 degrees for 10 minutes or so and you'll be good to go. Have a couple thin tipped flat head screwdrivers on hand to help as well. But don't worry about using them for screws ever again. Cuz they'll be covered in black shit.... 
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