So our mill has had an absolute ton of grain through it and it no longer pulls the grain down through to crush it. It just spins and spins and spins but the grain just sits on top, not going into the gap. I believe we have worn the knurls down on the rollers too much. Is this possible? Has anyone ever experienced this? What else could be causing the mill to just sit there and spin, spin, spin but the grain to continue to just lay in the gap and not get pulled down in? I'm wondering if I can purchase replacement rollers and be okay...