1. Undo 5 screws, no problem.
2. Undo 6th screw... Pling!
3. Spend the next 10 mins finding the bits that have just exploded...
Seriously though they're not difficult to service- you just need to be aware that the two halves are under a reasonable amount of pressure from the spring, and you need to keep them compressed. You can do this by hand.
Servicing is to simply remove the crud/old grease and then re-grease; however I can't remember at the mo what type of grease to use.