2004 FE450 forks

I havent rebuilt forks, but pulled them apart once for a look.
Losen the top clamps while they are still in the bike, a 22 or 24 mm spanner/socket will be required, cant remember which , but you can crack or losen the nut on the top of the fork before removing from the bike , then pull them out of the bike, then I unscrewed the nut completely, from the fork leg, it will still be attached to the internal part of the fork, the outer tube will slide down, then you will need to compress the spring down enough to get the 22mm open ender spanner onto internal component ,then let the spring go back up and rest against the spanner, the spanner holds the internal peice still, you then continue undoing the top nut further, the cap comes off, then remove the spanner holding down the spring, then it will come apart, I always lay the parts out in order on the bench so you know how it all goes back together again.Especially first time and not knowing how it all goes.
There is a bottom nut under the leg of the fork, there may be a rubber cover that needs to be removed with a flat blade screw driver first. Once the nuts undone, I think thats about it.

Someone else will have to comment on the technical side of what needs to be replaced with the internals , as i have no experience on this.Search the document on the site, plenty there on forks and components.