Pull that dirty stocker off and give her a look-over.
So far so good. No nasty leaks to be seen, no gnarly acid attacks from a battery gone bad...
This one is clean enough that any further elbow grease warrants removing the spring. That means lefty-loosey with the lock rings, while holding the top mount in a padded vise.
Spin the lock rings as far off/up as possible (until they hit the reservoir hose). Then invert so that spring and lock rings are again, as far up as possible so that you have clearance to tip the lower spring retainer askew and slide it out. You might need to push the bottom out bumper up the shock shaft to clear.
Now the spring comes off and she's ready for a clean-up. I like carb cleaner. Use what you like. Kerosene might be a bit more friendly on the rubber bits. Carb cleaner will definitely take off the OEM warning sticker, so consider yourself warned.
Now's where the fun begins. This is the factory "valve cap." The schraeder valve that pressurizes the shock is under this plastic cap. The ones I have done have been tight enough to require a bit of channel-lock persuasion that hints at a factory "do not disturb" perspective. In the end, I am going to use a nice metal valve cap both for appearance as well as protection during servicing, which you will see shortly.
Once you have the plastic cap off DEPRESSURIZE THE BLADDER by pressing in the schraeder valve. I suggest pointing it away from your face when you do this. Factory is around 150-180 psi, but if yours has any pressure at all (assuming never serviced), then you have just experienced a sign of encouragement. This means that the bladder itself should still be sound and re-useable.
Now that you have DEPRESSURIZED THE BLADDER, use a valve-core tool to remove the valve core and set it aside.
Now we are ready to remove the bladder. Keep in mind that oil should not come out until the bladder is removed. If any measurable amount does, it is a further sign that the rubber bladder is compromised. The bladder is held in with a circlip that you cannot necessarily see right off the bat. Let's put the res. back in the padded vise and snug it down LIGHTLY.
Here's where a couple things happen. We are ultimately going to tap the top of the bladder down to expose and remove the previously mentioned circlip. Before I do that, I spray a bit of WD40 to penetrate down into the interface, then I thread on that nice metal valve cap all the way and give it JUST a touch of snugness with a tool (barely more than fingers). The valve cap gives me a point to tap on with my hammer and push the bladder top down into the reservoir body. REMEMBER, you are working with aluminum that is not super durable, so if something isn't moving...
Here is the bladder top tapped down into the res. body and the circlip exposed.
And here I am with my bent up dental tool about to fish out the circlip.
Now that the circlip is out, we can wiggle out the bladder. It will be tight, so be patient, "walk it out", and try not to let the channel locks slip off the flats too violently (your goal is not at all).
Here comes the bladder. Get ready for that oh so sweet smell of two decade old suspension oil. No one needs to tell you that that is a bad smell...
And ugh...it looks like watery JB Weld.
Let's cycle the shock and pump all that crap out. There is nothing at this point that will fall into the oil pan. If something does...umm...you didn't need it. Keep doing it, you'll know when you're done.
Followed by a spray (or half a can) of carb cleaner and a wipe.
Congratulations. Now that all the bladder and all the oil is out, we are ready to disassemble the shock body. More to come. Mom says it's time for bed...