Not sure if they are hitting the tips or the deck. Deck spindles we're all rebuilt new bearings and seals, resealed the gearbox. All three are on the shaft properly and torqued to 72 ft lbs with three washers on them. I added an extra because they were spinning with 2. Spun all three spindles with belt on nothing was hitting aligned all 3 blades perpendicular to each other towards the discharge chute. Went underneath and sound the blade by discharge chute watched all 3 none were hitting anywhere even on the tips with the middle blade. Still have occasional grinding can't seem to get it to stop these are new blades from Kubota for this deck "Rc72" I think.