I helped wsjkawasaki change his shock oil on Saturday (1997 KDX220). Besides that, I have disassembled one '84 KX125 shock, three '87 KDX200 shocks, one '89 KDX200 shock and one '94 KDX200 shock.
You may or may not only need the dust seal and/or oil seal, but I suggest you just get a new seal head assembly, which is $39 at Race Tech. That is a little more expensive, but a whole lot easier. Your friends at Rocky Mountain have these from Race Tech.
Without opening it up and seeing the internal parts, there is no way to know what all is wrong or right with your shock. Using it with too litle oil can lead to problems.
The Race Tech Seal Head Setting tool makes things go a lot smoother for me. I have never used the RT seal bullet tool, but I have it and it looks great.
I haven't seen their shock video, but I have seen it on their site for $19.99. From what I have read 'round the Internet, it is the same video that comes with the Gold Valve kit for shocks. I have the RT fork video, and it is very good. The videos are not specific to a certtain model, so be aware that you are not going to see the tuner work on a KDX shock if you buy a KDX applicable Gold Valve kit.
MX Tuner has a good shock rebuilding article.
http://www.mx-tech.com has a 4616 KYB article that mostly applies to '89 and up KDX shocks.
You WILL have to grind off the peening to get the seal head assembly off. DO NOT drop the piston assembly, as all the little shims will go everywhere.
When you send it to Race Tech, you are already looking at $100 (labor), $39 (seal head assembly) and shipping cost each way.
I don't know if you are looking at buying a Nitrogen tank or renting one, but you will need a hose and a chuck. Since you will be pumping it up to 175-ish, don't skimp on these parts. I have read that a major concern is having it loose pressure when the chuck is removed. I know Race Tech and maybe Motion Pro have HIGH dollar chucks that supposedly do not allow it to leak back out.
I have called two dealers about Nitrogen recharging. One place quoted me $25, and one place quoted me $15. Not every place I called even offered that service, and I imagine some may not want to inflate shocks that they did not work on. I would not want a 175 psi surprise, either.
I have some information related to the C model shocks. A good bit of it applies to the 1995 and up shocks, as well. It is at:
http://jasonwhokdx.home.mchsi.com/Maint ... Shock.html
If any of it is confusing, let me know.
DirtRoller, I would like to see your info. If you can, please send it to me, also.
Thanks,
Jason