The first thing to do is to remove and clean the filter. Also, when the filter has been removed check the cavity for coins, fluff etc. Make sure that the drain hose, including the one connected to the drain motor, is clean on the inside. If you live in a hard water area there is a good chance of a blockage after a couple of years use.
Check that the drain motor is running when on drain mode. If not, then you require a new one.
Tony Stirling, August 2009