Well I have DD and SpinRite. I have made a SpinRite boot disk and burned DD to a CD. You said imaging the drives will be our last alternative, so what is the first step? Which is my best alternative and what should I make sure NOT to do.
I am going to convince the owner to let me take the Snap unit home for the weekend and attempt to repair it. If you think buying 4x 120GB drives is the way to go I can also try and get that cleared.
On a completely unrelated note...if anyone wants to play with a sick 4100 this weekend there will be free beer.

PM me for directions!