My dishwasher is emptying at the beginning of the cycle like it should but then when the water jets are supposed to kick in there is nothing but silence!! I have been reading other faults and tried switching it off and on and pressing the button in 4 times but to no avail. We have noticed in the bottom a black residue but cant find where it has come from. There are no kinks in the pipes and no leaking. We have also switched it off at the plug but nothing changed. My machine is Diplomat ADP8322.