I personally think that if your pump i making that noise just spinning it by hand, something is really wrong with it. Its probably about to fail. Sounds like the bearings are worn out. Is it weeping from the hole on the bottom of it? If there is any moisture there or drip stains, its seen better days. Do your self a favor and don't buy a cheap piece of junk replacement.(thats cheap insurance advice) Winters coming so make sure your antifreeze is up to snuff also. Hope this helps.
