Is there a way to reset all lighting in an assembly (or part) to default settings?  Sometimes I have to play with the lighting to make a .png for marketing (for example) and often times, it will get so out-of-kilter that it would be much easier to reset it.  Is there a way to do this?

I've tried going in and manually setting the ambient and directional to the same numbers that show up in an untouched new part or assembly, but this doesn't even always work.

Thanks for any help.