Replacing the fan in ReadyNAS Duo - possible?

I don't know if this applies your case, but here is how I opened my ReadyNas Duo case. Remove the four tiny screws from around the edge of the back of the unit. You can optionally remove the foot pads from the bottom of the unit in order to reduce the friction when you slide back the side panel. Then slide the side panel away from the front of the box, towards the back. It was pretty stiff on my unit, and I had to work at it a little bit. For access to the memory chip, you only need to remove the left hand panel (looking at the box from the front).