Okay experts, I need your help please. I have thick, lush St. Augustine grass that I keep high (4.0") and mow every 4 or five days. My Toro Recycler left a lot of stringers -- one every 20 feet or so -- even after I sharpened the blade and checked the RPMs. So I got an almost new Super Recycler with professionally set RPMs and freshly sharpened blade and I STILL HAVE THE SAME ISSUE. I've tried overlapping the rows and that helps a little. I've also tried bagging, and that helps a little as well -- though I'd much rather mulch. I am walking quite slowly when I mow, and there's no problem with the engine bogging down at all. I don't mow when it's wet, so that's not the problem either. Is my HOC too high to get proper suction? Is my lawn simply too dense to mulch cleanly? Is there some other issue? I would love the benefit of your thoughts. Thanks.