It seems whatever mower I use I endup having the same situation with my mowers. I may be cutting the grass when its too high or not putting my blades on right, although I think thats almost impossible, or just goin too fast? I don't know. When I make a pass it seems like I miss some grass between the middle blade and the outside blade. It happened with my 44" wb and my 60" zturn. Let me know if I'm just crazy or dull. By the way speaking of dull my blades aren't.