Well I spent a great deal of time trying to solve this very problem and I can tell you it is not missing a spacer. The diagram you posted is correct and you should not need to add an extra spacer or fab a new spacer if you have all of the parts listed on the diagram. I did use an extra spacer and it does work, but the hub will not seat properly and will allow dirt into the free-hub. Now I am not 100% sure what the problem is exactly as I do not have a detailed diagram of the DT Swiss 240 rear hub and would need several measurements to rule out that the axle has moved/shifted. I don't believe that is the problem. I believe the end-cap on the drive side wears out and no longer stops on the ridge it was designed to stop on, so when you tighten the skewer it pushes on the free hub causing it to bind. A simple fix that does not require removing the whole free-hub and cassette is to simply remove the cassette's screw in end cop and pull out the end-cap and insert a small washer that is just a little smaller then the inner diameter of the end-cap. I actually had to add to small washers, but it is working great after a few hundred miles. I disassembled the free-hub and was happy to see it was perfectly clean and no sign of abnormal wear. I will get a new end-cap at some point and see if that fixes the problem without the washers. Hope this works for you! Best Regards!
