Loosen the top cap, drop your forks. Loosen top cap completely and drop your forks upside down. Drain the oil. Remove top cap, preload adjuster and spacer with spring. Remove rebound needle (carefully) from the rebound tube.
Push fork tube (chrome part) and rebound rod all the way into fork leg (bottom part) Refill with fluid (should be less than 16 oz per fork). Make sure it's a cartridge fork fluid not just any fork fluid (like for dirt bikes, harleys etc).
Push rebound rod all the way down. Take fork tube (chrome part) and extend it up about. Cover the top with your hand and push it down (do this a few times). Leave it in down position. Pump the rebound rod a few times until clear ol will come out of it (bo air babbles). Screw the rebound needle into the rebound rod and leave it for 5-10min. After that check the oil level, start with 125mm. If needed, siphon some with a meat injector etc. Once you get 125mm, bolt everything back up.
here is your fork, obviously you don't need to take it apart that much
See zaq's upper picture, with the hands on the wrenches.
Now go back to and add a step 1 at the very beginning of the work.
Very gently nip down your external rebound adjuster to closed, as in full hard, and count the number of turns needed.
Then back it out 1/2 a turn.
This is all to make absolutely sure there is no way then needle can get damaged from over tightening during disassembly ( yes, it should not be possible to overtighten during disassembly but why take a chance).
Fast forward to reassembly time.
To the stage that you are about to remount the top cap/adjuster assembly to the cartridge rod.
Turn the rebound adjusters in 1/2 turn.
Back off the jam nut on the cartridge rod.
Very lightly and slowly run down the top cap assembly on to the cartridge rod.
As soon as the top cap assembly barely feels like it has hit some kind of internal "stop", do not move it further.
Back out the rebound adjuster 1/2 turn.
Run up the cartridge rod lock nut until it nips up on the underside of the top cap assembly.
Set the cartridge rod lock nut to tight.
Turn in your rebound adjuster until it lightly bottoms out.
Back out your rebound adjuster to the same number of turns you found at very beginning of work step A above.
All of this is about making sure the rebound needle does not get damaged by bottoming out during disassembly and reassembly, getting repeatability on rebound settings, and making sure the working height of the rebound needle rod is kept correct over multiple dis and re-assemblies over time. You can also do a vernier checks from the top face of the rebound adjuster screw down to the top face of the ride height adjusters. Until you had it apart, what you may not know is that the actual rebound "needle" is at the end of a long skinny rod that registers inside the cartridge rod. The needle and seat are not in the top adjuster cap assembly. Now go back to step 4. What you are actually feeling at this point is the needle at the end of the long skinny rod seating down deep inside the cartridge rod.