This was one of those truly freak accidents ... I bumped the cabinet while reducing the shed hair population on the bathroom floor, and the spare case, which I'd put there to remind myself to give it a thorough cleaning before storage, fell on the floor right in front of the ravenous electronic beast and was sucked up before I had a chance to register what had happened. And of course the thing was just that little bit too big to go 'round the rigid u-turn where the hose joins the machine (it had stuck about halfway, but I'd managed to force it to that end with the broom handle and could see it and even get hold of it; the broom handle, of course, also could not negotiate that bend to push the silly thing the other way).
P.S. I'm happy to report that the operation was a success ... and that the moron who decided that some vacuum cleaner hoses should be ridged on the inside as well as the outside, so that small plastic objects with their own ridgy edges would catch, lodge sideways, and not be able to simply be shaken out, is going straight to Shepherd Book's special hell to keep the child molesters and theatre-talkers company.