Stop the Affinity at the end of a cycle and unplug the power cord at the back of the appliance.
Remove the screws in the left and right sides of the control panel, which is at the top front of this model.
Pop off the top trim on the control panel using a flat-blade screwdriver. The control panel swings forward to expose the wiring and mechanisms underneath. The pressure switch is on the left as you face the Affinity, looking down on the exposed control panel. A clear, plastic tube is connected to a port on the side of the switch.
Pull the tube off the switch port. Secure the tube to the side of the Affinity with a piece of masking tape so it cannot slip out of reach.
Pull the two wires off the switch with the needle nose pliers, gripping the clip attached to the end of each wire. Tape the wires to the back of the control panel to keep them accessible.
Remove the screws holding the switch to the control panel. Remove the defective switch.
Secure the new switch to the control panel in the same position, using the screws.
Attach the wires to the two contacts on the new part.
Push the plastic tube onto the port on the new switch.
Raise the control panel to the upright position and secure it with screws in the sides. Snap the trim panel onto the top.
Plug in the Affinity's power cord.