how do I keep dispenser and door seal clean on Hotpoint Aqualtis?

How do I stop black gunge building up in dispenser compartment and also on door seal inside the drum? Not only black gunge collects all the way through the dispenser compartment but the dispenser drawer never fully empties of detergent or fabric conditioner. The door seal has a black stain which is almost impossible to remove even with the Hotpoint cleaner and the smell is bad. The washer is an Aqualtis AQGD169S.