Thanks L1ftmech- I didn't rebuild the cyl myself- I had my local hyd vendor do it. I trust their work- been using them for 15 years. I do believe they probably just ripped it apart the first time, not being overly observant, but after being apart 3 times, they looked thru it with a fine tooth comb. There was no gauging or physical issues with the cyl itself.

I'm thinking either a hyd pump or control valve, but with no symptoms I'm stumped. I'm gonna have to perform a search & destroy :)