Hi I just bought one second hand. The filter comes out easy. Unscrew the cover, you see a plastic disc with a hole in, put you finger in the hole and pull. There is a bit of resistance if the coarse filter is blocked. There is a seal whech expands as the cover screws in. Clean and replace. The other problem could be the door seal. Wipe in the gap with a cloth and dilute bleach. This often fills with mingin stuff over time, especially if low temp washes are used.
Kim, May 2009