I have a Ferris 48/21 1500z with regular stock blades. I have noticed many missed "string" type grass such as weeds. I can cut well maintained grass full speed and never miss a piece. I have tried raising the deck height and same prop. I have slowed down, same prop. I read something about mowing at lower deck height will help, is that true? I think blades or blade set-up is what I need. Thanks for the advice and ideas.