I have a Samsung bagless upright vacuum. The dust bin has a lid on the top (the back of which slots in to the main body of the vacuum). To clean the grille and filter this lid has a twist-lock kind of mechanism. If you twist it anti-clockwise it is supposed to unlock so you can lift the lid off. HOWEVER, I can't twist it!! I have got other people to try and it just seems like it is jammed tight. Would this be something under the warranty as I have had it less than a year.