Hi guys, When we got this 36" wright stander it was cutting great. We've had it for about 6 months now. It has 930 hours on it. I have noticed recently that it kept leaving a row of uncut grass right in the middle of the two blades. We took the blades to get sharpened, and tire pressures on tires are equal. What could be the problem? It leaves the uncut grass just about all the time when im going in a strait line.