I got a second hand trailer and in going over it noticed the wheel hubs are somewhat loose. Both wobble a bit when I jack the wheels off the ground, right being worse than left.
I removed the left wheel, hub, and bearings to inspect things. Turns out they were well greased with no corrosion. I didn't yet completely degrease them but having wiped them somewhat clean see no obvious signs of wear. (I wonder if this could be deceptive, however).
I then reassembled to see if I could take the play out. Sure enough, I could turn the castle nut just enough to snug things up and line up with the cotter pin hole. It seemed like it was turned just one notch more than when I took it apart.
Was this just a case of the prior service person not making sure things were tight? Having done this, the wheel feels just a little tight when rotating and I'm not sure if that is expected.
(Note - I will correctly re-grease the hub, replace the cotter pin, etc. before use)
Edit - the second wheel was even more poorly adjusted. The castle nut could be turned 2+ full turns before getting tight. Seemed smooth once I did this however.