For a 310 I pulled the bottom cover plate off the dishwasher and found that there is a small connection chamber of the main plastic body (opaque plastic about 60mm square). This connection chamber connects to the float switch by a 6mm tube. The connection chamber had filled with gunk and the float switch was no longer seeing the water level change.
The connection chamber unclips from the main body and is simple to clean out with a screw driver and water.
Be careful when reinstalling it as there is a small O ring that should be on the large 13mm inlet pipe. This can be dislodged on removal and stay in the main body. If the O ring does not come out with connection chamber you will need to pull it out with your small finger and slide it over the 13mm inlet tube
Mark Bennett, February 2009
