FredR

Hmmm - not difficult to understand why the coupler has failed prematurely. It seems the root cause of the problem is misalignment of the inner sprocket - the underlying question now is why this happened and whether it is a systemmic issue or a one off type of thing. The outer face of the inner sprocket needs to sit slighly proud of the pullley outer face to ensure the cover plate does not bind but clearly the sprocket was engaging less than half the width of the coupler insert.