I am nearly finished reinstalling all eleven of the cylinders on a 97 SL500 like yours: here are some of the things that I have learned:
1) Take snapshots of everything you can regarding the installed configurations of every cylinder before you remove it. You will be removing and reinstalling much of the interior of the car. You will not remember which clips and pins go where, or the order in which they need to be installed. Write down everything you do, step by step, so you can reinstall in the reverse order. Some things need to be done in a specific order for convenience; otherwise they may interfere with other operational steps. Label each hydraulic line with masking tape. A few can be reattached incorrectly, and if you do so, you will have a devil of a time trying to sort things out at reassembly time.
2) Be very careful not to lose any mounting parts. Plug all holes with paper towels where stuff can fall. I neglected to plug a small hole beneath the lower mounting bolt for the main cylinder. I thought there was no way that huge bolt could fall through that tiny hole, but it did. I could not retrieve it with my magnetic tool or with magnets attached to my flexible drain reamer. I was fortunate to be able to buy a replacement bolt from my dealer for $50. I'm still waiting for it. It would have cost a lot more than $50 to have a machinist manufacture a duplicate bolt. I also lost a 6mm pin and am waiting to get one from Germany, through my dealer. I searched diligently for the pin when I lost it, to no avail. E-clips are notorious for flying away and disappearing forever. Buy a few 6-mm e-clips on eBay now. Do not be surprised if you end up needing a couple of them. Also buy a metric e-clip inserter tool. It will probably save you a couple hours of misery. Tape the e-clip to the tool with masking tape each time you try to install one.
3) You will need a set of 1/4-inch drive torx sockets. Also, a magnetic retriever tool. Very large (9 to 12-inch) tweezers may also be helpful.
4) Klaus, who will rebuild the cylinders, is very helpful when you run into problems. He usually responds to urgent emails. His excellent detailed instructions for the removal and installation for each of the cylinders may not be absolutely clear, and his pictures may not exactly represent your model. You will probably have to improvise occasionally. You will also encounter a few seemingly impossible situations, but everything can eventually be worked out.
5) While you are at it, take the tank off the reservoir and clean out all the sediment. Then flush your hydraulic system a couple times to eliminate the 20-year-old fluid and sediment in the lines.
6) Use lots of rags to keep any fluid from dripping into the car. It will take a lot of effort to get rid of the smell. Clean up every drop of fluid you find. Then wipe up with Greased Lightning or some other strong detergent to eliminate odor.
7) A tiny flashlight is indispensible.
8) If you tackle the whole job at once, you won't have to go back and do a similar job another half a dozen times in the next few years.
9) Every time you get discouraged, keep in mind that if you take the car to your dealer, he will be glad to fix the whole hydraulic system (excluding the roll bar) for $5000 to $6000. If you do it yourself, it will cost you about 1/10th as much, but you have to spend a few days of labor.
10) Odds are probably about 50:1 that your 'no other leaks' comment is extremely optimistic. I thought I had one leak, but I found eleven, including two that the dealer had replaced less than four years ago for the previous owner for about $1000. Forum members tend to agree with Klaus that his rebuilt cylinders will easily outlast OEM cylinders. Also keep in mind that OEM cylinders might already be deteriorating while they are on the shelf at a dealership. I forgot to write it down, but as I recall, the two OEM replacement cylinders that were installed for the previous owner in 2013 were factory date stamped around 2001.
