what do i do to my dishwasher to get clean crockery?

Well, first I would check the filters and the wash arm, most wash arms just pull off. Check all the holes make sure they are clear. Get some SODA CRYSTALS from your supermarket, they are about 50 to 80p a bag, put half in an empty dishy just sprinkle on the bottom of the machine, put it on the highest temp and let it wash.
The soda is like a water softener and de-grease agent, it will clean all the internal bits, filters and pipes, spray arms etc and it is cheap and as good as CALGON. If this works do this operation once a month, as it called a maintenance wash, you could do the same thing with your washing machine as well, but with a washer make sure it does not do a cold top up before it empties, if it starts, stop it select drain and spin
Hope this helps.

IanB
September 2009