It should of come out with the white threaded cover. It must be stuck on some rubbish in there. If you can't forcibly remove it then you may have to get at the pump body and remove the pump from the other side. Probably by tipping machine back against wall and get at it from underneath. If you take a hose off the pump first you will be able to catch some of the water into a bowl.
Lincoln Appliance NZ, December 2017