First, I watched a video. Seemed easy enough. Then I took my KitchenAid Pro 600 apart and looked inside gear box. Exactly like video. So took apart and cleaned used parts. Bought new and had to take one quick look at parts sheet when they arrived and reassembled. Loaded with grease, cleaned it all up and gave it to church. Machine broke because I was using it for bread and the machine is really not intended for someone who makes a dozen loafs a week. So I purchased a KitchenAid Commercial unit and it works just fine.