[wingnut60]

If the wheel is wiggling/loose on the axle--it is time to change the bearing. Nev-R-Lubes are pressed in and you will have to have some manner of pressing it out/back in. Might be best to get the bearing in hand and take the hub to a shop.
They aren't serviceable, just replaceable. Get on etrailer.com and look up the bearing--you will need the 50mm one, not the 42mm.
At the age of the trailer, I would arbitrarily replace all of them. You cannot change bearing style to a conventional grease-packed bearing without getting new axles--the spindles are specific to the Nev-R-Lube.
Do you have the electric drum brakes or disc brakes? It may be easier/less trouble to purchase the drum/hub with the bearing already in place--get the replacement hub/bearing, pull the old one, put the new one on and done.