[dibble9012]

Left the oven on to keep the temp at 250F. Also, up to 12 minutes would be fine to leave the light inside the oven on a piece of cardboard. I did 10 minutes for the second headlight and it was much easier to open.

It's a careful balancing act. If you don't heat it up to much, you can still get it apart but you can distort the housing too much while prying. Leave it in too long and it will soften the housing too much. It has to be just right to have the glue soften enough, but the housing not soften. 10-12 minutes is perfect as it takes minimal prying to get apart.