Best thing to do if your up to it is check the connections to the door lock, may be loose or rusty. 2 ways of doing it. Remove the front pannel or just the rubber seal around the door (may be tricky if you have big hands). Removing the front pannel is tricky, you'll have to find the screws to take the top off, control panel, kickstrip, rubber seal around door then the front panel. Open up the rubber seal around the door by locationg where the spring is aound the metail ring that holds the rubber in place. carefully use a flathead screwdriver to stretch it out and then the rest of the ring will come out easily. The rubber should be easy to remove. locate the clip with wires that goed into the door lock and carefully unclip it. Have a look st the connection and terminals and give it a clean or rewire if possible. If it is the lock and the door is not loose when it shuts, you may want to look for a replacement and fit it yourself. In this case you will have to take off the front panel.
shaz
August 2008