Our m/c is about 5 years old and has started to leave brown gunge on some of the washing. It can be rubbed off as soon as it is removed from the m/c but if left to dry only washing will get rid of it. All the waste pipe seem clear but there is a brown sludge inside the door seal not a great amount of it though. Could it be a mechanical problem or would running a very hot cycle help to wash it out? Thought initially it was contamination from the dish washer of dirty water being fed into the waste pipe but the inside of it seems clear. Would appreciate any advice.