Bosch dishwasher not pumping out water?

Bosch Exxcel
SGS45EO2GB/45

At the end of the cycle the pump keeps running but does not pump the last of the water out.

We had this problem before and found a lot of sludge in the pipes that take the water into the machine - so water was overflowing and setting off the anti flood device. After cleaning and draining it all worked fine.

This time it was doing the same pumping continous action, but we found the pipes to be clear and no water in the bottom of the machine. I've taken all inlet pipes off and cleaned them, also done the same with the outlet pipes. I've checked the impellor and nothing is blocking it. When I lift the red arm to make the machine drain I can hear the pump going but watching the water go round the pipes I can see that it is not taking the water to the top of the tube and over to drain out. Is it a problem with the pump or something else I haven't checked/thought of?