Help with identification of an old Zenith?

[oldzenith]

Hi everyone, my name is Paul and I'm new here.
My mom has an old Zenith TV and I am trying to identify it without much luck. From some Google searches it seems it might be an early to mid 1950s model, but I haven't found an exact match yet. I also could be completely wrong.
It's a Zenith, marked as a Royal "X" Chassis on the back, but I don't really see a model number.
It's black and white, no color, says it has UHF and VHF, and is about 22" x 27" x 36".
It does work, but I can't get the horizontal and vertical adjustments adjustment right so the picture will stay put for more than a few seconds at most. Of course I really don't know what I'm doing either.
I did manage to use a transformer as an adapter and then could even hook up a DVD player to it. It's playing Avatar in the one pic that should be attached.

Can you guys help identify this?
Also, what would be the value, at least roughly? My mom might be willing to sell.
Any help will be appreciated.

Thanks.