You are supposed to dry the door seal and leave the door ajar with any washing machine. If you don’t then you get a build up of black mould (not grime) on the door seal. I clean mine with cheapo thick bleach, use gloves, wipe around the seal with kitchen paper and get into all the folds, then add a squirt of thick bleach and wipe around again leaving plenty of the bleach all around the seal. Put another squirt in the detergent drawer and run it on the longest hottest wash you can. when its finished, run it again empty so you don't bleach your clothes. I also do old clothes or dusters or non precious whites in the first wash load just in case.