I'm having bad clumping problems using my 60" zero turn exmark. Even cutting 3-4" of dry grass with sharp blades. I use high lift blades and I'm cutting at a height between 3.25-3.5". Tires are properly inflated and the blade tip speed seems to be fine. I've been told that doubles will help with this, but I've been told it will cause extra wear and tear to the spindles. What else can I do to help with this situation?