The customer didn't know what a hub was, but was attempting to install a part in it! No surprise the customer is having a problem. I would think most who work on their own bikes would know the name of the part they are working on. I may not know all the names of the bits and pieces inside a hub, but a hub is not exactly a part which most of us would have trouble identifying. And if I didn't know, the LBS would likely have an exploded view, or I could find it online.