This is pretty much a symptom of an aged hard disk drive, and not much you can really do. You may be able to get it to start working, but likely only for a short period of time.
You should look for a replacement drive if you want to continue using your computer. There are lots of various options from SCSI2SD to Jaz and Zip drives, to another old aged drive, to putting a SCSI3 server drive in with an adapter.