Not only did I replace the Planetary, but also the Transmission Housing (recommended). The biggest challenge (which really wasn't an issue) was removing and replacing the snap ring. The most time consuming aspect of the whole job was removing and replacing the food-grade grease, and overall cleanup of the unit. The repaired mixer works like a charm! Well worth the time and effort; and a lot less expense and hassle than sending the unit in to Kitchenaid!