"IF your spindles have gotten out of alignment, ie bent or moved, the blades may wack each other. If this happens grind a little off the ends of the blades." I disagree. IF this is the case you should fix the spindle problem, not unbalance the blades to adjust to something else that is broken on the mower. I use the Leaf Gobbler also & this is a great tool during leaf season. Like TPI said make sure the blades are tightened down at a 90 degree angle to each other. I have had the best luck with regular under gator set up.