Firstly - I'm pretty new to bike maintenance, so forgive me if I use the wrong terms. I recently got hold of an old Saracen Terratrax, and the FH-M290 freehub is rather rattly. The noise and the resistance are noticable enough for me to want to repair or replace the part (although I think the physical effect on cycling is probably negligible).
The part looks like this:
I removed the cassette to have a look at cleaning/oiling the freewheel body, but found no way of removing it from the hub. Spraying copious amounts of WD40 and dripping oil all over the thing seemed to reduce the resistance in the mechanism but the noise is possibly even worse now. I thought I might be able to remove the freewheel body and get at the bearings where they connect to the hub, to try to flush it out, but I'm now getting the impression this part can't be removed (although I can find spares online so I'm quite confused).
What's the cheapest way of resolving my issue, and having a nice silent rear hub?