The debris catcher is located at the bottom right corner of the front of the machine. It is usually difficult to open by hand. Use a wide pair of pliers and carefully turn it anticlockwise for about two complete turns until you can pull it out. Before opening though, place a tray underneath and have some paper towels handy as there is about a cup of water to escape once you manage to make a quarter to half turn. When you removed the key/coin/etc. from the debris catcher, make sure that the white seals are clean before pushing it back and screwing it in (by hand it should now go). The small black square marker needs to be at top position when the debris catcher is fully screwed back. I'd watch for any leaks during the next washing and if there is none, fit the plinth back too.
Laszlo, December 2010