The shaft is apart of the front face of the waterpump. That sounds really dodge though, maybe the part they replaced it with was faulty? They're only about $50 to replace (This was a quote from an auto shop for a new 4ac RWD waterpump, I don't know if this is the complete pump or just the front half, as when I got a new FWD waterpump for $70, it was only the front half) and isn't exactly a hard job, good luck!