My MDFS came from school - as I left it was replaced, luckily after looking after it for a good few
years I was able to keep it. I've had to fix it a few times :(
The PSU in my MDFS passed away - thankfully it did no damage when it died, and it was an
easy process to graft in one from a PC. I must write it up properly but it's possible.

I've put some not very clear pictures of the process here.
PSU Images.