Have you checked that the arm that spins round at the top isn't blocked? You can take this out and rinse it - it's usually (in my house) blocked with pieces of sweetcorn. Odd, as we don't really eat much sweetcorn ...!
ooh i didnt know the arm itself needed cleaning, will check thanks, are they easy to get off? - yes, i do make sure it can move otherwise it makes an awful noise Am running it at the moment empty but will also get some of the dishwasher cleaning stuff, thanks everyone