Silly old me should have read the manual and realised these fancy filters were servicable items needing periodic replacement. Not to worry, saved in the nick of time from the missus chucking this quite expensive vacuum out of the proverbial window. Thanks and praise to 'yourspares'. For a few quid our vacuum sucks like a monster again, the pitch of the motor has reduced a by couple of tones, and the lid does not fly off, negating the need to hold it on with gaffa tape. All round result, many thanks.