Thanks for the quick response and really appreiciate the help!
So i took a look in the drain hole cover off, taking out the sump and checking with a light. Having read your response i was expecting to see a hair clip or something in there BUT it was absolutley clear?
Any other ideas? maybe its something stuck on the other side but it looks like a sealed unit?
After a little movement and a few more washes, the clicking has stopped!
i re-opened the drain hole to take a look and there was a tiny stone (definitley wasnt there before). so i removed and hey presto! its an odd design as there seems to be a plastic propeller to the rear which im certain was flicking the stone around now.
Thanks for the help!