Repack them, remove hub cover with straight edge tool ie. flat screwdriver. Remove axle nut retainer, remove axle nut, remove thrust washer, pull hub assembly from wheel gently slowly, outer bearing may fall out off end of spindle have a clean cloth or something to catch it, you don't want it to fall and hit the ground or concrete. You don't want any dirt or contaminants in the grease or on the bearing.
I use a seal puller to pop out the old seals for the inner bearing. I like to clean my bearings in mineral spirits, jmho, some just push the old grease out and new grease in. I like to be able to inspect the bearing races which are pressed into the hub and I like to inspect my bearing cages and rollers for signs of excessive heat, cracking of cage, or scratches and gouges in the race. If any of these signs are present I replace the bearing and race. If you replace the bearing replace the race also.
I'm sure the ASE mechanics and shade tree professionals will point out anything I may have missed or they disagree with
Clean your bearings if they look good repack them with grease by hand or with a bearing packer, use a seal install tool or block of wood and gently tap a new seal back into the rear of the hub after installing the greased bearing.
Installation is reverse of removal. Now I will state what the "Dexter Axle rep" told me about seating the bearing and seal. Setting the" bearing pre- load", per dexter axle, "While rotating the hub, torque the axle nut to 50 ft. lbs., stop, loosen the axle nut 1/4 of a turn, This should make the nut hand tight, you should be able to spin the hub by hand, if not it is too tight. Replace the nut retainer to the nearest place, which with castle nut is a flat spot on the axle shaft with cotter pin and drilled axle nearest slot in axle nut.
I am sure there are some who would disagree with this torque spec. It does sound high but for reference it is the exact same procedure and torque for the axle nut on the rear of my Chevrolet 2500 full floater axle nut and bearings.
If you have a different brand of axle than Dexter it would be best to check with the manufacturer and find out what that axle bearing pre-load is.
This post is not aimed at you pros it is aimed at the DIY who may lack a little confidence in their ability to repack their own bearings, Good Day as Paul Harvey used to say.