How do I access pump on Tecnik 795/3 dishwasher?

I have a built-in Tecnik 795 dishwasher which stopped working when trying to empty following its initial rinse. It did so with a loud clunk and so I suspect that a mechanical fault has occured with the pump. I have removed the unit from its built in position but now I can't see how to access the pump by removing the unit enclosure. Additionally the unit is still full of water and this does not syphon out of the discharge tube, presumably because a valve is closed. Any advice, please?