I have the same problem on my G665SC. I checked to see if the filter in the inlet valve assembly was clear and it was. You should look at yours, its an easy task and should be in your machine instructions on maintenance.
An Enginner call out for £45 stated the inlet valve was faulty. Replacement cost quote £137 for material (Valve, hose and electric in the hose is only sold as complete assembly) plus labour £15 on top of the original £45. A normal machine inlet valve only, as fitted on a washing machine, can be bought at a repair shop for about £10. I am thinking that I can make a replacement assembly this way but I need technical information on the details of the faulty one. Project ongoing.
John Gard, December 2007