Mine too!
You do not need any special tools other than the star type screwdriver. These are available from tool shops anywhere. You could tease one out with an ordinary flat screwdriver and take it with you to get the right driver as you will need it once you have the cover off.
There is a wealth of information on the web, including a very good parts manual. This shows how all the parts fit together and if you study that, you will see how to take it apart.
After you have the cover off, and before you start to take the rest of the boiler apart, you need to do two things, first is to cut the water supply to and from the boiler by turning all three black taps off at the bottom and then drain it using the valve at the back of the pump. Don't forget to close that valve again or you will never get pressure when you are refilling.
I hope this helps
Alan
Alan, February 2008