It's worth a try to get a turkey baster and empty out all of the old
PS fluid that you can, and try the Lucas stuff along with new PS fluid.
It can swell old seals to stop some leaks. It isn't a sure fire fix,
but If you read the fine print, I think that they will reimburse you if it doesn't work, so save the sales slip and the packaging.

I bought a used 740 that "needed a rack and pinion" for a bad leak.
After cleaning all the crud from there it turned out that one of the PS
lines was leaking with a tiny pinhead leak, so I just needed to replace
a single hydraulic line instead of the rack. This was a fast leak and not one caused by a worn seal that would usually be a slow leaker.

Bill