Hello Graham, my name is George..The large 100mm x 70mm object you mention on the end of the supply hose to your dishwasher is called an aquastop.. This switches the water feed to the appliance off in the event of a leakage.Can you provide the ENR of the appliance you have.. This is normally found at the top metal part of the door.Kindly be patient whilst awaiting any responses from me as I'm not constantly available.
Ive taken the m/c out and theirs no rating plate it only says Neff 3 in 1
The dish washer is a Neff s5555xogb