Just bought a new DS Lite on the weekend. It is absolutely superb, but I seem to have a slight problem with the right shoulder button. It works, but it does not have a positive 'click' in the same way the left one does. Has anyone else had this, and is it likely to get worse as I use it? I am reluctant to swap it out, as the machine has no pixels or other issues that I have read about here. I'd hate to swap it for one worse!