Thanks for your reply, ck.
Unfortunately, our kitchen is so small that I couldn't get around to the other side (base) of the machine to see what he was doing.
He ran a stiffish piece of cord through from somewhere inside to the front of the filter, which removed a lot of gunk.
He then blew through from a pipe he'd connected somewhere inside which came out at the front.
I've taken the back off now and found two tubes running off the manifold. One of them runs up to one of two parts which look like pictures of pressure switches I've seen on the web.
I've taken the tube off there, blow through it successfully and also attached a tube to the switch and blown into it, producing an audible click.
I've tried a test wash and that managed to stop filling, so hopefully I've made some progress.
I'm trying an empty 90° cycle now, with detergent, which will hopefully clean the innards out a bit.
Adrian Jones
April 2008