I have psoted this on that other site as well, I have seen many posts on replacing the top cylinders on my 69 but nothing about repairing the cylinder. Has anyone got any suggestions?
You might try a local farm implement/repair shop. I know they rebuild hydraulic cylinders all the time. The real question will be at what price. New cylinders can be had for just over $100 and assuming new seals can be sourced for yours, the cost plus labor to rebuild will most likely exceed $100.
Jody,
Did you put new cylinders in your conversion? If no, keep an eye on them, they can leak without leaving much of a sign of doing so. I found one of the pieces of cardboard that I put on my life rear pads to be getting more and more oil soaked and was scratching my head until I figured out it was ATF from the PS cylinder 
Anyway, if you did buy new ones (and since you are a cheapskate like myself), what was your best price? I found next step performance on feebay puts them on sale now and again for a little less than $100, but ended up buying them in my Xmas MU order. With the 10% off and shipping spread across the other stuff I bought, it ended up being a better way to go. About $106 each with the 10% off.
Sorry for the hijack, but it is on topic at least!
Bob: I scrounged a set from a FOX body stang from the local part yard for $20 thinking I could make them work, but they are way too short. But here’s a fluid free idea- I’m looking at the screw mechanism on these Jag power seats and me wonders if those things are powerful enough to haul some fat guys arse (plus the weight of the seat itself) to and fro, up and down, they might be powerful enough to raise and lower a convertible top. The screw part could be made as long as necessary and the electric motor would allow for very precise operation.
P.S. Bob, could you measure the stroke on those cylinders for me?
Jody,
Sure, will do.
Jody,
8" stroke, 3.5" center to center from eye to mounting holes when collapsed.
Bob
I looked at getting my old ones rebuilt at a hydraulic shop a few years ago. They said that they were not rebuildable because of the way they were manufactured. They were meant to be a throw away part. (I did not like that answer either, but I knew and trusted the guy)
I bought mine from Convertible Service (Convertibleparts.com) http://www.convertibleparts.com/hydrauli.htm
I just replaced both of mine this past summer. Pain in the ass getting out the “pin” on one of them. The other just slid out.
Good luck.