I had similar problems with my roca it was slow filling sometimes not at all and cleared the valve so now ok.
So if in hard water area it may be lime crystals problem in the outlet of the water inlet valve you could try cleaning with an old toothbrush or you may have to turn off the water to the cistern and open up the valve and check the washer too isn't limed up. while its apart replace the washer after clearing any signs of lime crystals
Bob, February 2014
