Help please!

Series 111 LW
I would appreciate any assistance in this matter. I frequently head off to the woods to collect firewood. On every occasion and on entering the woods I engage low range/four wheel drive due to the terrain. After collecting I head off back home and dis-engage back to 2 wheel drive for normal tarmac driving. I reckon on this occasion I have forgotten to dis-engage and the issue I have now is that when I engage either low range or hi-range 4x4 and try to move off, after half a wheel rotation either forward or reverse I get alot of resistance and come to a grinding halt! Can anybody tell me what is going on. I can drive off and reverse in normal two wheel drive.

jack front end up and check to see if wheels ,diff ,drive shafts feel okay ,remove front prop and try it in 4wd if it still locks then problem will be in transfer box

Sounds like "Wind Up". Not a wind up... but the condition brought on by using 4x4 on normal roads in a vehicle not fitted with a third differential. All the "backlash" is taken up in one direction, because you're driving on hard ground and the average distances travalled by front and rear axles will differ when cornering causing stress, "windup" in the drive line between axles including the transfer box. You don't get this on soft ground because the wheels can slip.

Jack up any one wheel and it will unwind. Or try driving off a kerb so one wheel is suspended free to unwind.

Many thanks for your suggestions, I will try them out....