Board Thread:Questions and Answers/@comment-4197661-20130209234526/@comment-6294495-20130210181826

Go into the fillers Gui and pick up one of the bricks and replace it, this usually resets it. The green light should come on at the top of the filler, even before power is supplied. If you are clearing an area, you don't need it hooked up to a chest with a pipe, as in your screenshot.