Outer Limits 4x4 Board

I went wheeling the other week in my cruiser, bj73. 5 speed with the vaccum actuated transfer. started off onto the track fine then gradually got harder and harder to change gears. then once back on to easy stuff and back in 2wd it was changing fine. no noises or anything coming out of the box or the transfer. has anybody got an idea because i haven't got a clue.

i would start by checking and changing gearbox and transfer case oils. this helped a hell of alot on my gu ute gear changes were alot smoother and sounded alot tighter as to speak.
just a thought jonesy

yeah i was thinking that but i thought if it was that then it would be hard to change all the time. could be low on oil in the transfer itself possibly then as it gets worked and hot making it lubricate less. hmmmm that could be it. seems pretty obvious now. cheers jonesy.