I called the factory as I wanted to be sure it wasn’t a safety related issue before I make the 500 mile homeward bound trip tomorrow.
Mark in customer services was very obliging and talked me through the issue. It relates to a lack of suitable grease (preferably graphite) on the splines of the output shaft and at the inner taper and the inner nut thread. The grease effectively acts as a damper and if there is inadequate grease it permits a very small amount of play which results in the aforementioned clonking. This is exacerbated with hot temperatures; hardly a problem in Normandy as the weather has been wet and cool!
I hope this information helps others. I will wait until I get home to resolve the issue but at least I know it is not a safety issue.
