that's one reason I usually replace them.
They newest revision is a little different part number and I'm told is improved.
When rebuilding most folks toss new seals in them and send it. But there's more to it. There's bushings, and then there's the bore itself. The bore must be round and not tapered and not scratched, if it is, it's worn, will never seal up properly and will require replacing the cylinder bore. Or machine it, but honestly probably just cheaper and better in the long run to replace the assembly.
The seals and bushings were over $240 the last time I bought them, plus some tools to get it apart and then check the bore and bushings and rods, then downtime, then finding the time to do the rebuild, etc....and a new cylinder was about $800 and as said, updated.