Sourcing a replacement HDD wasn't so easy, none in Australia that I could find
I'm having trouble trying to figure out why you can't get a replacement HDD? Are you running a totally obsolete computer setup? HDD's are usually pretty cheap and easy enough to acquire.
I'd respectfully suggest that a 6 yr old HDD is not far off internal destruction anyway. I seem to recall that the quoted figure for average HDD life is 7 yrs.