I know this is way too late to help you Angela but it may help someone else. I had the same problem and found that as well as taking out and cleaning the pump, you need to remove the black rubber pipework that connects the drum to the pump and clean out the ball valve thing you'll find in there. Mine was full of surprising debris (including 22p in loose change!). The junk stops the ball (which should be there by the way :)), from dropping down and allowing the water to escape into the pump.
Martin
June 2013