This is what my bedroom slide looks like as far as the hydraulics are concerned. First picture is the anchored end of the ram, the second shows how it pushes/pulls the slide in and out. If the slide end had come unbolted the ram would either push the slide out or punch a hole in the outer wall. It would also not pull it back in once it was out. Your unit may be somewhat different but the basic idea is the same I am sure.
If the pump is working and other slides are moving as they should, then you should be able to hear the ram moving if you are in the bedroom. I suspect somehow there may be no hydraulic fluid going to that ram.
