Roller jacks.....
It's amazing at how many jack failures can be attributed to a bad o ring seal.
It's such a simple hydraulic system. I rebuild a lot of my tools. This world isn't geared around that mind set, but if you've got the ability, you can save yourself a lot of cash and keep from rolling the dice on something else that may just fail again.
I wish the tool companies out there would spend some time manufacturing components without assembling every single one, so people could have the option of buying components.
The only reason I had a friend make a U joint for mine, was because the only way I could get another one from Sears, was to buy the entire ram as a unit for $100.