Blades. "Similarly, I don't think it's a mystery that sharp blades produce the healthiest and most manicured lawns," [Jay Gaskins] adds. "Sharp, balanced blades are also critical to the life of your machine. Unsharpened blades cause unneeded stress to pulleys, spindles, belts, engines, gear boxes and clutches. Additionally, unbalanced blades can cause abnormal vibration, resulting in spindle or gear box damage, not to mention long-term damage to the cutting deck components."