The Silencio 850 pressure switch (float) is located in the door, with a rubber hose running from it to the sump (bowl) under the dishwasher. This hose has 2 blue caps inside it to regulate pressure (so they are meant to be in the hose). The pressure switch is a round black item close to the top of the door, just under the door-lever panel. To take the main (lower) door panel off, open the door and unscrew the screws on the sides, working from bottom of door to the top (so you know when you have undone enough of them to free the panel).
A pressure switch may be available from Electrolux (NZ) for about NZ$30-$40, but you may need to order through a service agent or registered merchant/reseller.
Henoch
June 2008