http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_189604_langId_-1_categoryId_255223
http://www.youtube.com/watch?v=QuLExeu3UEM this was very important - the cube / piston needs to be wound CLOCKWISE !!!
Must have been the pressure I was applying that got mine back in slightly when turning anti-clockwise