zanussi D/W safety valve

im pulling my hair with this one.
I was called in because it would not fill so i released hose off water valve worked for one wash. got called back. I then thought blockage in the manifold,so i changed it which comes with new valve. Tested D/W fills with water for 30secs then no water but valve is humming so pulled hose of to top of valve there water from it. Checked hoses to front seem to be clear.The only thing i can think there is a blockage any help or tips on where to look?