Hubs Not Locking

i own a 98 ford ranger 4x4 i jacked it up off all 4 tires to see if my 4wheel drive was working. i looked and the front tires were not moving i checked it out a little closer and found out that its not my transfer case its just the hubs that are not locking. so i figured that i would just take it in and get em replaced. untill my neighbor told me that i could rebuild them. is this possible? and if so how can i get started?

i have a 2wd ranger, that said i heard fords auto locking hubs are worthless. Most of the posts i read people just replace them with manual locking hubs