Am I ever glad to see your post! I have the same jack to restore (Walker 770 ) rebuild and I would be grateful to know where you found your parts. Seals , gaskets reassembly info.
I Dad bought the one I have from a scrap yard and paid for it the pound. He had it for 25 years, and I have had it for another 20.
Please respond at your convenience.
When I was in my teens I use to pick this thing up and carry it around to where I needed it, over the years it has gotten heavier as I get older.
I refuse to get rid of it because I knew eventually I would find the parts to rebuild it.