It is easy to do. Look at the back and there are two discs at the bottom corners of the unit. Use a sharp point to remove the sticky tabs protecting the screws and remove the screws. Flick up the GPS arial and there are 2 more. The case will now prise apart. Once open there are 2 more screws to release the circuit board. 1 bottom right and 1 middle left. Remove this and the board will come out. The GPS arial connector simply flicks off. Take care not to pull the wire.
Alex Papas, August 2007