Dyson DC05 - replacing catch on motorhead?

The catch/lug on the motorhead floor tool (itself a replacement for the original in Oct 07) has snapped, meaning it won't hold on to the extension tube. dyson kindly sent me a replacement catch. However from a subsequent conversation it transpires that these later motorheads were 'strengthened' with no visible means of opening them, and Dyson claim they are not user-serviceable. As the motorhead is otherwise US, I'm temped to prise off the casing around the release button - but thought I should ask first if anyone else has had experience of this? Thanks!