Hey Steve I hope you figured out your situation. I'm working on the exact model same leak situation. Top seal pretty much a glacier one retracting the cylinder. By any chance, can you help me out on where you got your seal kit?

Here's how I do the lower 2 seals. Remove forks. Chock the wheels so the machine can't roll. Lift the carriage so it is about 8' high. This exposes the 2 lower chrome shafts. Take a 2' length of 4X4 and place it inside the outer channel so that it will support the center channel. Take a 4' length of 4X4 and place it inside the center channel so it will support the inner most channel. Lower the carriage until the channels hit the the 4X4 supports. Now chain the carriage to the mast which will be about at 6' high. If you want to prevent a massive oil spill you can remove the bleeder plug on the top of the cylinder and push the lever to down position. You can strap the lever with a bungee and give it a few minutes. That will allow a lot of the oil to drain back to the tank before disassembly. Remove the four 1/4" head 12 point bolts that hold the manifold on the very bottom. They are recessed up in there so you need a socket. Remove the two 3/8" bolts and nuts on the sides of D that hold cylinder in place. Lift the small chrome shaft and remove the snap ring and the 3 keys that hold that lower foot on. Remove the snap ring under part C that holds it to the cylinder. Remove the eight 12 point bolts that hold C on and remove part C. Now it's ready for the seals. The small one is easy because the gland nut the holds it is threaded on the outside of the shaft so it will go in without any threads rubbing it. The bigger one is like the ones on top where you have to use or fabricate an installation tool to prevent damaging the seal. Note that gravity will want to make the shafts drop so be aware. It is handy to have someone help you hold the shafts up as you remove the foot, C, old seals, new seals. After it is all done bleed the air out of the cylinder up top at the bleeder and walk out saying to yourself "that's the last one of them I'm doing"!!

Ah, long winded, all being said, when these components are suspended or off of the load of the cylinder... it's a virtual guillotine. I used several safety straps and clamped steel blocks to ensure that if anything let go there would be multiple physical barriers in place to protect my arm fishing around under there.
Good times,
Steve

As it goes, the condition of the other seals became kind of a joke here. I've been in "Clark Lake" for a month or so, learned a bunch, been beaten up, etc. If the seal that shattered like glass when I tapped it out is an indicator of what the other seals look like... maybe we have a day... maybe we have a year. It was a few minutes. The next upside seal is leaking, most likely from all the twisting and banging around to replace the upper seal. It's not a geyser, but I'll have to replace all the seals which is fine. Since I've had a fresh look at actually how the mast lifts and what's involved, much easier. Unfortunately my pals within range don't have triple lifts to extend this thing all the way. Again, clever chaining etc can get the cylinder out and or the whole mast for service. I do have the ceiling height to play around with and a couple of pals with lifts. All is good, the seal part is no problem, its just rigging everything up to remove or support heavy components that is the trick.
The most confusing thing of all of this is that after having this lift for 15 years I never actually looked at how the mast works. Today after lifting it there were several "Ah ha" moments. I've always looked at the load and never at the mast action and components. Don't remove hex or 12pt bolts from "C". Alignment is a pain.

I will add, I had a high beam (35"), a come-a-long, various chains and straps to help with lifting and aligning the mast sections and or extending the cylinder during this. I did not need to really do any of this just to replace the top cylinder seal, I was preparing to remove the entire cylinder. With another lift and knowledge of how the mast sections move I could have lifted the mast sections so "D", the actual forklift frame attachment and "C" the final moving part were separated. Under "C"are the nuts for the side bolts in little pockets cast into "D". there appears to be a circular plate in the pocket of "D", which I have not tried to get at, or see if under this plate are any of the bolts that hold the manifold to the innermost and thinnest ram in the hydraulic cylinder. "E" is not the innermost cylinder there is another one inside that one that lifts "C". The dealer had the diagrams and will print them for me if I like.
Steve

Again, thank you. The lift is together and working! The local Clark dealer here in LA, Cal-Lift, was able to get the right seal kit and all the information about the lift for me. I used thin sheets of plastic to make the cone that protected the seal from the threads on the way in. A little tapping on the bronze guide with a drift got it in far enough to engage the threads on the gland nut. Once the mast was up I could see how those two spinning bolts on the side of the mast work. Still have not seen how the manifold connects on the bottom of the cylinder but it will be much easier to check it out now that the mast can go up.
Celebrating a day without being covered in oil.
Steve

Thanks for the help. It's actually a 25D model. I was able to blow out the bronze guide and chip away at the seal. I couldn't figure out how to get to the manifold bolts. I put a mirror under there and felt around, it looks like there are bolts but they come from the top down, and I can't lift the mast to get to them. 8m going to just replace the seal with the cylinder in there.
In any case, I'm searching for the seal kit, can't find the model number on the cylinder body, there is a place nearby that will help me match it tho. Hopefully.
Steve

Did you remove the aluminum block on the very bottom of the cylinder that the hose connects to? It has 4 screws that require a 12 point 1/4" socket. As for leaving the cylinder in and replacing the seal, it can be done but is very difficult. **** a sharp screw down into the seal may make it so you can pull the old seal out. If not the chain down and pull the lever will work. The problem will be getting the new seal in. There isn't enough room to push the seal in without it rubbing along the threads that hold the cap on and it can damage the new seal. There is a special tool that is shaped like a funnel that is used to make the installation easy. You may be able to take some thin feeler gauges and install them all around the outside of the new seal to help install. Be careful, this is about as dangerous as it gets working on forklifts.

That all being said, if I chain the black outer cylinder down and give it a little blast would the top pop out with the leaky seal? Could I replace this without having to remove the entire cylinder? It is the innermost upper piston.
Steve