Then went to empty the canister of its admirable/ appalling load of dust. (Really, if dust is made from skin cells, I wonder I have any epidermis left.) And on the side, in white print I had never noticed before, was a box with an arrow and the legend: 'To maintain peak performance empty dirt cup and clean filter after every use.' Filter? Oh, this button here that says 'Press to access filter'? I press. Inside there's a filter on a piece of plastic sponge. Who'da thought? And the one downstairs? Same filter, completely clogged with dirt. So I take it out, and on the side of it these words appear: 'For best performance change filter every six months'. Six months, not years- even for someone as lackadaisical about vacuuming as I am.
So now I have two functioning Dirt Devils, go me.
(The 'clean filter after every use' message is absent from the downstairs unit. Obviously the company got tired of the mechanically challenged complaining about their 'defective' vacuums that wouldn't clean any more, and demanding refunds.)