80 manual hubs not engaging

They worked fine until one day it was cold and ofcourse AFTER I got stuck I locked the hubs, moved the lever in 4hi-4lo and nothing.once I got pulled out, I drove about 100' with the brakes applied lightly to generate heat thinking for some strange reason the hubs were froze and it engaged. so without a rocket science degree, I figured my hub were frozen. Its happened quite a few times after that as well.My question here is could there be moisture in the hub? Is the hub going bad? it never made a sound, pulled,slipped,nothing.I'm kinda hesitant on taking it apart because I have no idea what I'm in for. I've never even seen the inside of a 4x4 hub and want to know if its a relatively job? Could it just need to be cleaned and repacked? If so Would I clean it with a brake cleaner? I'd like to know what I'm in for incase I'm out of my league. I have a wide range of tools so thats not an issue. Thanks in advance. if I can get a straight forward answer anywhere I know its here

I'd buy a Haynes repair manuel so you can see what your dealing with, and what tools you'll need. Maybe repack the front wheel bearings and check for excessive wear on the hub engagement parts is the place to start.1980 will have disk brakes.

The problem with haynes is they don't go into detail. I'm aware it has disc brakes. I only mentioned the brakes because it seemed to be heat thats what helped engage the front axles. I'd just like to know if possibly moisture could be the cause and at what a fix would entail. Thanks for the reply

Sure. The hubs could be rusted and/or worn. Remove one for inspection. They R&R rather simply.

Sure. The hubs could be rusted and/or worn. Remove one for inspection. They R&R rather simply. As I remember the 3/4 ton has allen screws to remove the cover and locking center stuff. I dont remember about the 1/2 tons. Also check for broken gaskets (seals) which would cause the water entry.

mine has the hex bolts as well. Thanks for the replies guys. I'm gonna give it a peek and see whats goin on in there