Miele W 4840 Operating And Installation Instructions page 36

Cleaning and care
Once the flow of water stops:
^ Remove the drain filter.
^ Clean out any foreign objects or lint
from the filter.
32
^ Check that the drain pump impeller
(in the back of the chamber) rotates
freely by spinning it with your hand.
^ Return the drain filter and tighten it
into place.
,
If the drain filter is not securely
tightened water will leak out when
the machine is used.