I had a family member borrow 2 saws the other day with out permission. He used them to cut several small stumps down, flush to the ground. When I got them back the chains where very loose and dull. I resharpened them and tightened them up, but when I started to cut with them they would go into the wood about 6 in. and bind up. When I pulled them out you could see where the cut took a sharp turn and binded. These are pretty new Stihl bars. I flipped one over and tried it again, but it just turned the other direction. Any idea what causes this? I figured the rails are uneven or out of whack, is there a way to fix this?