Bicycle Tutor

I have a Trek 4300 with Shimano FH-RM40-8 for the rear wheel hub which i am trying to service. It makes 1 knocking sound on every spin. Got a few questions:
- Can the Body Fixing Bolt be removed from the Freewheel Body? If yes, how?
- Is there any trick to to remove the balls from the Freewheel Body? Can't seem to dislodge them as easily on the other side.
http://www.paul-lange.de/produkte/shimano/support/explosionszeichungen_archiv/FH/FH-RM40-8.pdf

To remove the freehub (Part 14) you undo bolt part 12. This requires a large 10mm Allen key inserted down the centre. Hold the wheel, insert the Allen key down the centre and make sure it is inserted far enough. You will probably have to use the long section and then put a tube or spanner on the short end. (right handed thread)
To remove the balls I just poke around and flick them into the centre QR hole. Push them through and out the other side. (The grease holds them in place.) Some Shimano hubs have seals which can make it awkward to get the balls out but none are shown on the diagram.
You say you get a "knocking" every revolution.
How is this showing?
If it's only doing it when you are pedalling then I doubt it is the freehub.
It may be a cracked ball or ( as happened to me) something completely different.
I thought it was the hub but it turned out to be a slack spoke clicking when the tyre was pumped up hard. (once every rev' of the wheel.)