i had same problem. there is a plastic grommit that fits in the hole of the washer bottle and the pump pushes into this with a snug fit. If you cannot see the grommit anywhere like mine it may have somehow gone into the washer bottle. I
Ended up taking washer bottle out of its position ( one highly visible screw holds it in) and hey presto there was the grommit bouncing around inside. if not here it may have fell under the washer bottle when pump was removed, if not here then a new one will be required (or scrap yard job).
Ian
August 2007