Hydraulic bottle jacks are generally a PIA due to most of them are manufactured "over seas" these days. I have one from the early 70's that still works fine however I also have a newer, larger one bought about 5 years ago that is like yours, worthless.
I have found that most things from Asia that have rubber components won't last too long. Although most of the raw rubber in the world comes from SE Asia, they don't seem to have figured out what additives they need to add to make it last more than a few months.
I have used the mechanical bottle jack from the truck for years for emergency trailer work until I purchased one of the aluminum trailer aid products.
Any chance someone nabbed your TPS sensor?
2016 Duramax - 2010 CF30SKP
Viet Nam Vet 70-71 Da Nang
Real airplanes have two wings and big, round, engines