My experience with our "82 310 was & is frustrating. Left front leaking. Re moved piston assembly but it wasn't obvious how it came apart. In an effort to not do damage I took to hydraulics shop for rebuild. OK fine. Ten days later I reinstalled with much effort, (this is the hard part) only to find it still leaked. Removed again & returned unit. Everyone is sooo sorry for my trouble.
Four days later reinstalled (did I say this is the hard part?) it still leaks, not much but it leaks. I've been told to return it . Sure & maybe I will when I get my breath. A year has passed & I don't recall what they charged but it was very expensive, maybe $300-=$400.
I have the PDF file on the HWH system & contact info for them somewhere.
I believe they wanted $600 for a new one. Good luck, Pete