I don't have an M2 Ritter but it sounds like you need to resharpen the edge as opposed to touching it up. Did you use it a lot before putting it to the Sharpmaker? You may need the diamond stones. M2 is hard machine steel. If all else fails find a local knife shop to grind a new edge and touch it up with the Sharpmaker or send it to BM for "Life Sharp" service.