not a project, but a rebuild - stumped by unidentifiable leaky jack

I purchased an older patient lift ("pacific patient lifter") to use in the shop recently. Mostly to haul heavy stuff around, but, it leaked. I decided to rebuild with new seals. Did that, and it still leaks...it leaks worse! Has anyone here ever seen such an inline plunger design before? Am missing a seal on that plunger? The only thing holding the pressure in the plunger assembly is a park quad ring acting as a cylinder oring. please see video for details.



Thanks for any insight.
Barrett

 

I read these are supposely better than O-Rings. Could it have twisted/rolled as you were installing it. I have had that happen in the past when I was working with Hydraulics. We would use some grease to help hold it in place and help prevent from coming out. Another option would be go back to a standard O-Ring and use some Nylon Style Packing. These are sprial cut.