Can you post the model number please.
Also does it seem to get hot during the wash and dry setting?
Ok if its heating up ok then it rules out a heating fault.
What you need to do here is remove the bottom basket and from there you can access the lower spray arm. Remove this and you then need to give it a good clean out. Make sure all the holes in there are clear. If blocked you need to poke something in there to clear the holes. As if they get blocked it knocks the balance out of the arm and it stops it from spining round and when this happens you get poor wash results and it can stop dissovling the table as the spray arm sparys the water into the dispener to dissolve the tablet.
So try that first and see what happens and let me know.