Not to get off the subject, but I have used the sealer type PS fluid in my Ford 2000. I belive it was Prestone brand. It was just something to try to get by, until I had time to tear in to it. I filled it up, and ran for about 4 or 5 hours that day. Decided to power wash it off when I finished. Not sure what's in that stuff, but it hasn't leaked since. And that's been about 8 years ago... The only time I've had to add, was when I installed the Aux. transmission in '03, then to replace the clutch last winter, and lost fluid when I split the tractor.
But I'd try the O-ring and packing first.
The only thing I've had rebuilt were my trusty old Walker, and Hein-Werner brand bottle jacks, and that's been over 20 years ago, and they were old when I bought them at auctions.