Found your questions a few days ago when looking for the answer to this question myself. Im no technical engineer so excuse my lack of technical terms below and if you already done this.
I had same problem on mine on off for last 6 months but today I think fixed it. First check the waste pump filter (its not really a filter) you can access from the bottom of the front of the machine under the flap on left side by unscrewing the plug, have a bucket for the water that will come out! Mine this time wasn't blocked but has been before with coins and did solve the problem before. I then took the back panel off and where the waste pump leaves (top right side) you see inside a clear rigid plastic pipe that has the bend hose to outside the machine. This snaps out pretty easy with a screwdriver and remove the hoses from both ends and the little one on top inside. In this I found two 5p coins and some other debris, clean this under tap and put back together. Machine done a wash since all OK. The whole thing took all of about 30 mins. Might of already done this but if not hope this helps.
Bob
January 2008
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