Received the HDD sent by Roo so proceeded to pull the PC out of it's nook (or is that cranny?)
Unplugged my 'dead' HDD, couldn't get it out, so just put roo's in the next slot, plugged in and booted up.
Got confused when I found all my data, to realize I'd plugged in the wrong HDD, but it seemed to be working now.
Still don't trust it, so in the process of transferring necessary data to the new drive.
In that process, during a reboot, windows ran some DOS program that deleted some (a shit load) of duplicate files and repaired a whole heap of others.
Boot time is back to SSD standards.
Some weird shit been happening, so I'm not counting my chicanes yet, but that's where we are now.