Stuart have you looked at related questions on this site? It has been answered I think.
I too had an AL03 whilst still in full service warranty. It was the drain pump being blocked by small piece of debris.
The engineer used a piece of stiff but bendy plastic strip and gently forced this through the drain hole below the filters. this pushes past the impellers of the pump and frees it, apparently a common problem. he also provided an improved filter which touch wood has stopped further blockages.
Alan
November 2005