The full reset, in order
Start with the detergent drawer. Most pull all the way out with a small release catch. Soak it in hot water, scrub every channel with an old toothbrush, and pay attention to the little siphon cap for the softener compartment, which collects the worst of the sludge. While it is out, reach into the empty housing with a cloth wrapped around a bottle brush — there is almost always residue up there.
Next, the door seal, which is where most of the smell lives on front-loaders. Peel the rubber lip back gently and wipe right into the fold with a damp cloth. Expect this to be unpleasant the first time. Get out any hair grips, coins and ancient tissue while you are there.
Then the filter. On most front-loading machines there is a small hatch at the bottom front. Put down old towels and a shallow tray, because water will come out — quite a lot of it. Unscrew the filter, rinse it, clear anything trapped in the housing, and screw it back in firmly. If your machine has been draining slowly or leaving clothes soaking wet, this is very often the culprit.
Finally, run an empty maintenance wash on the hottest cycle your machine offers, with no laundry inside. You can use a dedicated washing machine cleaner or a scoop of soda crystals. When it finishes, dry the seal and the drum edge with a cloth.
