Thanks Guys (or Gals?)

I had an brain-wave and tried the Norton Utility Emergency Disc - it booted beautifully (if painfully slowly), I asked it to search the SCSI network, and it couldn't find anything there - so it does look as if the hard disc is the problem.

I'll go procure the long screwdriver - may take several days however ;( - and then try tapping the wretched thing, as suggested, and will report back.

johnboy