I've had my Kitchenaid Professional 6 for some time and eventually, the planetay head detached and fell off. Along with ordering a replacement, I ordered replacement gears as well, just to make sure everything was good. Sure enough, after removing the gear cover, some of them had damage. The entire process to replace the planetary and gears was simple. The only time consuming part was cleaning out all the old grease before re-assembly and greasing all the new gears. Also grease leaked past the old gasket into the body, so I had to clean that up as well. The only tool I had to purchase was some snap ring pliers, which I found a pair for $5 at a local hardware store. So again, besides dealing with the grease, it was quick and painless.