99 esof was able to shift into and lock into 4hi but not able to get it back into 2hi - after much trying it finally disengaged but then I tried 4hi again and it locked in and now I can't get it back to 2hi. What's going on? How do I disengage?

 

is the drivetrain bound up? try backing up straight about 30 ft.

 

Same thing just happened to my '97 F-250 PSD. I noticed that each time I used 4wd (mostly to pull a big boat up a slippery, steep ramp) it became increasingly difficult to disengage the front auto hubs. Finally the left hub locked up all together. I took the advice offered here and switched out to Warn Premium Manual Hubs. Easy to install, and so far no more problems.

 

tryed the backing up 30ft - no luck - I can shift from 4 lo to 4 hi but not from 4 hi to 2hi. Took the hubs apart and they seem to be functioning.