This low mileage car was towed into our workshop with the concern that it would not move. Initially it seemed that the clutch may be defective, but upon further inspection we found an internal transmission problem.
It seems that Mini only presses the ring gear into the differential carrier hub, rather than bolting it in the traditional method. I suspect that the ring gear is heated, to cause it to expand, and the carrier is chilled to cause it to contract, allowing a slip fit. Fortunately we were able to repair the transaxle, saving our customer a considerable expense. While the transaxle was out, we replaced the clutch as it was quite worn. The early Mini clutches do not have a good reputation for durability.