I dusted off an old Argos scart 3 to 1 switch box this afternoon which I bought a couple of years back to hook up an xbox and dvd player to a single av1 rgb scart input on telly. Suprised to find black screen on selection of av1 input (neither source appears). Sound comes through fine, as does the widescreen signal when switching between sources. I also noticed the source appears for a spit second before displaying black screen when selecting and deselecting av1 on telly. Also tested on portable in dining room, same problem. Is it broken? Or have I forgotten how to use the thing over the two years? Any help would be appreciated.