DT Swiss sells a special tool kit for removing and installing the bearings and other internal parts in the 240 S hubs. It's expensive and I can't explain why but I bought the kit. It would make better economic sense to take the hub to a shop that has the right tools and service than to buy the kit. I've ridden a set of 240 S hubs for 10 years and have had no reason to service anything other than greasing the ring gear (ratchet). I did have a rear drive side flange break though.