Thanks so much for all of your replies. Here's an update:

Still not working.

Mike: When off the ground, (when snapped into horizontal traveling
position), it rotates the wheel until the wheel hits the frame of the
trailer, preventing further rotation, then will not rotate any further.
Either direction. Jim: same thing. Don: same thing.

Gene: I think you're right, but I cannot get it to re-engage into the
nut inside the tubing. It is impossible to rotate the case that holds
the caster and jack rod because it is welded to the bracket that holds
it all onto the tongue.

I think tomorrow I will jack it back up with my car jack and try to
immobilize it and bang it back into the housing to try to re-engage the
jack with the nut.

You guys are great!