Thanks Roydon. We had an E8 error code so I followed what you said and freed up the cogs. It seems to be working again...I will try to upload some additional images to help anyone else as dismantling the valve is slightly tricky but if you take your time and dont force anything open such as the...
after removal of plastic plate and the cogs that are inside it- microswitch is box at left- you can gently turn the cog at centre and it opens the microswitch