I have an 85 chevy blazer that was converted from the factory full time hubs to  Warn manual type ( steel) my problem lately is that when I 4 wheel I'll hear a loud "pop" on the driver side front wheel and I instantly lose the front wheels. When I take apart the front cap everything seems to be in order, put back the assembly together (at the house ), and the  4 wheel drive works. Then I was pulling a trailer last week in some soft sand, and It happened again! From what I can tell the locking hub uses a spring to push in a star type ring to engage the wheel. Do these springs wear out ?  Any info would be appreciated!  

my truck is dooing a very similar thing. I dont lose my front axle when it does it it just keeps poppin.  im gonna replace the hublocks and wheel bearings if that stopps my popping out in the axle ill let you know...

I kept the factory full-time hubs on my trucks, and never had a problem with either - highway or off-road situations. I figured 'why mess with something that works for me' - just my opinion.  

It could be a simple as two  much grease. Warn says that to much grease will keep the hub from fully engaging.   

mine was the wheel bearings the ones on the passenger side were completely gone that was my problem sorry i couldnt be more help