Have a 2 year old Exmark Radius with a 60” deck, been running low loft blades. Hit something while mowing, machine has a vibration it didn’t have before. Checked the blades, center blade had a good sized nick in it. Put my backup set of blades on it, vibration is still there. Seems to cut fine. Any idea what to check next? What if I continue to run it this way?