You can't.
Unless........
You cant if you don't first understand how the system works. And I finally tired of spending so much of my time coaching people thru the same steps - so I had a thought,I would write a long thread detailing how the top system works. Problem is, my thread is focused on finding bad sensors. Your issue MIGHT be a bad travel sensor on a cylinder, but I can't say, because you didn't tell us the ONE thing that would confirm it - when the top stopped moving, did the pump keep running? (You can hear it, did it go silent or did it keep making noise?)

If the pump went silent, we either have low fluid in the pump or a bad travel sensor somewhere.
If the pump kept running, it's low fluid.
If it is low fluid, putting more in will get it working - but you will still have a leak and that will be the next thing we deal with - but let's do this one step at a time.

We need the answer to the above before we proceed.

Anyway, here is the thread I made - but again, did the pump stop or did it keep running?
CLICK HERE for my attempt to create a readable thread on how the sensors work in the top system - photos of their locations included because the service manual's sketches suck.