Product review (1 stars): The part does not work.
An exercise in futility. This product does not fit our Pro600 mixer and I'm truly disappointed as it is supposed to be a genuine item from the manufacturer. A side to side comparison with the old one shows that the shaft of the replacement is marginally longer and as such the hole for the pin and the groove for the washer are out of spec. As a result you are unable to reassemble the mixer as I found out. I ended up using Loctite on the old part (in my case the shaft was separating from the planetary) and it seems to be doing the trick.

I'm disappointed KitchenAId; I'm not ready for a new mixer as yet and it seems that's what they're forcing me into doing.....