Similar thing happened to me 2 weeks ago on my JFK-LAX...except my delay was only 5.5 hours
Does EVERY part DL needs for MX have to be flown in from ATL? I know SAN isn't a hub...but JFK is...wouldn't you think they'd have a few extra parts (let alone a spare a/c!) lying around there at least (as well as at CVG and SLC)