To clean the solenoid valve:
1. Remove the valve as described in Exchanging the solenoid valve.
2. Clean the membrane using water and cloth or a soft brush.
3. Clean the O-rings.
4. Clean the recess of the membrane in the valve block.
5. Remove dirt from the boreholes of the O-rings.
6. Apply grease and put all parts back as described in Exchanging the solenoid valve.