Bit of a thread revival, but I just rebuilt my 40's and there's something I need to add- Following the above service guide, the entire process is very simple and straightforward. They say the dampner unit is 'sealed', but what a load of shit! As shown above, it is very easy to pull apart, inspect the bladder for nicks etc (mine had actually popped out a little, and there was alot of play in the unit).
New oil in the dampner unit, reseating the bladder (again, very easy to do) and boy the forks feel FANTASTIC! Of course with new dust wipers, and fresh oil in the stanchions. I was going to send these off for a service, but spent $70 on some seals + fork oil instead. Took maybe 1 hour tops to redo the entire forks.
In summary- read through the guide, if you have all the tools needed and feel confident, then I strongly recommend having a go yourself. The only tricky part was the high speed compression knob- behind that ball bearing is actually a tiny, tiny spring! Don't loose it
Also I should add a rant about overtightening here- I have never yet had a 'clean' rebuild of a second hand pair of forks, simply because people tighten things waaaay too much. For these 40's, the previous owner (who had his own mechanic, bloody hell where did he learn how to do this) had over-tightened one of the crown bolts, the hex head was stripped and an ez-out couldn't undo it. Ended up getting my housemate to drill the head out, and he needed a new pair of undies when the bolt head gave way!! The ez-out worked a charm after the load was removed. Buy a torque wrench, and freaking use it! Don't tighten anything as hard as you bloody well can- you will just damage the bike!
Also there is a crack on one leg (thankfully in a non-load bearing location) because this 'race mechanic' had tightened one of the pinch bolts so hard as to crack it. Of course one of the bolts on that side is stripped...
Bloody hell, the pinch bolts only need to be a little tight, A LITTLE! DONT CRANK THEM!!!!