Help needed with Ariston A1436?

Hi, can anyone help me resolve the problem with my wahing machine?
It has been starting to stop when draining the water at the end of the cycle, where sometimes you had to switch it off then back on using the power button on the front to get it to complete the cycle.
Now when it tries to fill at the start of the cycle the water briefly enters for about half a second then stops.
When investigating things the pressure switch showed signs of malfunction with black sooty type of material around it and on the small pipe from it.
I have replaced this with a new one and removed a lot of debris from the drain pump but to no avail.
Of course the extended warranty I took out when I bought it ran out at the start of the year, so any help would be appreciated.

Andy
June 2010