the machine turns on and it gets as far as this - on one of the screens

sometimes it comes up with a error "unable to write to heartbeat"
I have spoken to barcrest tech today and they said the pc hard drive is corrupt.
as its a section 16 machine with the old style pots in the top box im guesing it will be very hard to find a hard drive to copy?
is there anyway i can save the hard drive i have?
or worst case could i convert it to a b3?