How can i fix sdw60 dishwasher on ecl flashing error code?

We keep getting the eco flashing light on the dishwasher. When we have looked at the drip/overflow tray in the bottom of the dishwasher (If that is the clear plastic chanber underneath the float mechanism)it is full. If the machine has been off for weeks and then I turn it back on it does work for one wash and then it goes back to eco flashing light. Next to the clear chamber there is a dark chamber that looks like its got mushed up baked beans in it! Can we clean this? Does this need cleaning? I can't see how to take off the tray to empty it, I have taken the pipes off but it is still full. Please help