Can't be fixed - replace it. It's a 30 minute job plus however long it takes to scrape the old gasket off (fricking forever on my car!). NAPA will have the metal pump for ~$70 - had mine in for 1/5 years and 38k miles with no problems.
If the cone inside the pump is loose just firmly press it back into place - you'll see what I mean when you get it open.
Scott
