Help with floor jack, leaked and won't pump?

So I have this cheap Harbor Freight (please don't hate me) "trolley" floor jack. This is the one that has the removable handle and fits into a grey plastic case. I have probably had it for 10 years. 2 ton. It rolls. So last couple times I pull it out to use, I see oil/hydraulic fluid inside the case so it must be leaking but it still worked but I began to notice that I had to do more pumps to get it to raise. Now yesterday I use it and it goes up a few inches, then stops pumping? Meaning I lift the handle to pump and nothing happens, but it still holds the car up.

I do still have a little baggie that came in the case that has an oring. But I can not figure where the screws are? Help me out I am a retard. also I don't have hydraulic fluid handy, can I use something else? tranny fluid? brake fluid? power steering fluid?