L4701 4WD engagement, what's the trick?

[Fladogman]

Just go the opposite direction for a few feet and it should shift fine. You have to get the tension off the gears before it will shift. I do this all the time and it always works

 

[CobyRupert]

You need to have the front axle “unbind” with the rear, that is, move the lever when there’s no torque in the driveline.
Sometimes stopping and rocking, or backing up, or turning wheel unbinds it.
Sometimes there’s just a brief moment when there’s no torque in the driveline.
Best method is: when driving straight and on relatively flat ground, press the throttle or hydro pedal to give tractor a little “burp” of speed and then let right off.
When the tractor is in that sweet spot when it’s neither accelerating or decelerating, the torque in the driveline is zero and lever should slide like butter.

 

[Fallon]

I generally engage my diff lock while moving before I need it. That way teeth are moving & will lock up. Don't engage it when 1 wheel is spinning or it will grind & slam in breaking things as it tries to lock up the spinning wheel to the one with traction. A little motion with both wheels moving is good, a lot with only 1 is bad.

If you are already stuck, try to engage the diff lock. If it goes in, great. If not, bump the go pedal to spin thing internally so gear teeth line up better then try again.

Just realized this was about 4wd & not the doff lock. But I do 4wd the same for the same reasons. Generally gently engage or disengage it while moving slowly & not slipping.