I blew up our "Professional" Kitchenaid after 3 years. Replaced the brushes, disassembled and checked everything, no dice. Called Kitchen Aid. They pretty much shut me down on warranty or reasonably-priced repair. Not cool for a $300+ item, in my book - the proposed repair would have cost as much as a new mixer, with no warranty on that work either.
So long story short, I googled "Kitchenaid sucks". Try it and see what you find...
Sarah and I did a bunch of research, and discovered that in the late 70s Kitchenaid was a division of Hobart - which makes industrial equipment, and welders, and all kinds of great stuff, all in the USA. Then Hobart sold the name to Whirlpool/GE, and the quality went downhill fast.
Long story short, the vintage mixers from the Hobart days all still work great - and are hard/expensive to find. We got a smoking deal on this one - only $215. And it's 35 years old!
But it's a Hobart, so hopefully it'll last another 35. We'll see.