I have a whirpool WMC321 (Service no 8570 321 15611). It has been leaking a small amount of water from time to time but recently this has got worse. I have taken the back off the machine and all the hoses etc look fine. The water seems to be coming from a round hole in the centre of the back of the drum. It appears to be a drainage hole. Any idea why this should be leaking or how I can prevent it? Many thanks