Just finished changing out the fan in my Linkstation 250. A couple of notes on the instructions given elsewhere...
-- The exact replacement fan is available from Mouser Electronics
-- You have to peel off the front panel overlay to find the two small screws that hold the U-shaped band around the case. When I removed the panel on my Linkstation there was enough "sticky" left to put it back on when I was done. (Note that the two screws are really tiny - about the size of a grain of rice. You will need a cross-head jewelers screwdriver to get them off. The screwdriver in an eyeglass repair kit might work as well.)
-- The U-shaped band is held on to the case with L-shaped clips on the top and bottom legs of the band. After you remove the two tiny screws hidden under the front panel overlay, slide the U-shaped band toward the front of the drive (I had to pry mine with a screwdriver) then lift the top and bottom arms up until the clips clear the case and the U-shaped band should come right off.
-- To open the case, press in the tabs that lock the sides together and swing the case open like a book where the front panel is the spine of the book and opens last. The two halves of the case should come apart easily leaving one half containing the electronics, drive, etc.
-- The fan is held in with plastic clips built into the case. When you remove the fan note which side the label faces so when you install the new fan you can get the airflow in the right direction
-- There are three wires on the fan - red, black, and blue. I simply cut the wires to the old fan and spliced in the corresponding wires from the replacement fan.
-- When you reassemble the case, be sure that the power switch on the front panel is aligned with the corresponding hole in the front panel of the case.
Good luck!