Have you looked at the mechanical seal which sits on the shaft from within the pump casing?
Usually this is the main cause for a leaking pump! If you go to the original equipment manufacturer they will advise you to buy a new pump. This seal only costs about £25 each!!! Consider replacing the seal before splashing out on hundreds for a new pump!
Look here for more info:
http://www.mechanical-seals.net/mechanical-seals-for-shower-pumps/
Hope it helps.
Lawrence, July 2009
