[dave in australia]

One other cause for the taper not gripping and relying on the key is some form of lubrication between the axle taper and the hub. I heard some old timers say to use a bit of grease on the axle before installing the hub. This doesn't allow the axle and hub to grip each other through friction, which is what a taper relies on. When I bought my tudor, this was one of my rear end tasks, as well as a lot of work on the brakes just to get them up to a safe standard. Never assume the prvious owner knew anything about A's when they worked on them, let alone knew anything about mechanics in general.