mobility scooter tire flat

kind of a long shot, my mom's mobility scooter developed a flat and i'm trying to fix it

feel free to let me know if there is a better community for these kinds of questions

is the valve stem supposed to be loose? is it missing some kind of O-ring, it doesn't seem to seal to the wheel rim
can I replace the valve stem with an inner tube?
and if someone happened to recognize the model of this scooter that would be nice too, it was just dropped off by a family friend one day with no paperwork