Hi, yes it is easy to replace the fan, I used a Sunon Miniature Fan 5VDC Square 25 x 25 x 6mm 2.2 CFM 2 Wire Leads, I cut the wires from the connector, leaving plenty of wire to reattach and then soldered the new fan to the wires and connector.
Not sure where you are but there is a company on ebay uk that has these at a good price.
£3.99 each inc shipping, I am sure you will be able to find one and they are a fantastic replacement.