If I measure engine RPM, using a laser type tachometer at the screen covering the flywheel/cooling fan, am I getting a true RPM reading? Or do I need to measure it at the output shaft? Or somewhere else altogether? I have been having a striping problem(unmowed stripes) with my mower. I got the majority of it fixed by leveling the deck, and a company rep sent me some blades to help troubleshoot. I put the blades on, I think they are Gators, and I think they are so heavy and create so much drag that they caused the striping to come back way worse than the OEM blades did, by(it seems to me) reducing the engine RPM severely. I checked the RPM and I am getting a reading at about 3550. The manual says the engine operates at 3600. When I engage the OEM blades, not even mowing yet, just engaging the PTO in the garage, the RPMs drop to 3520 or so. My main question being. Is that 50 RPM, at full throttle, enough to show up or manifest itself as a mowing quality problem? Or is that considered within a tolerable range? I know I can just bump it up and check, but I can't really verify for sure, because the grass is pretty much going dormant for the year. So I can't get a real world, everyday cutting observation until spring time. Any experience in the matter is much appreciated. The engine is a Kohler Courage, 23HP, with about 125 hours on it. Purchased new in March of this year.