Well with this failure rate, I think it's worth it. specialtech don't seem to stock it, but I found one here; http://www.overclockers.co.uk/showproduct.php?prodid=WC-209-EK
That's the one I should get right? It will also replace the current one and fit in my setup nicely without having to change anything. Still going to be a pain to drain it all and flush the radiators again.