Hydraulic jack seals....source?

How many of us have tossed a floor or bottle jack simply because it would no longer pump up? I have a 20+ year old bottle jack on my press that's no longer working that I'd like to replace the seals on. Looking for a good source. Most of these units are coming out of China these days, and maybe so 20 years ago, but I'm hoping that by measuring the bores the seal sits in and by taking into account what type of seal it is (square, wiper, round, etc. I can find something to match. Ideas? I know the ram on my engine hoist could use new ones, too, as well as a nice but non functioning floor jack I picked up at a garage sale.

http://www.blackhawkparts.com/

Thank you as I have a $5 floor jack that will not pump up

Here is a place you can try:

https://www.hcrcnow.com/

^^^ noted, thank you!

Found some at a place called Lazzars.Got a 4 ton Sears floor jack for 5 bucks.Seals were like 12 bucks shipped.Rocky