4x4 not engaging

[vidio1]

So like a lot of the US we got some snow in Western Kentucky over the weekend. It finally slowed down and was expected to stop soon and like most tractor owners I decided to grade the driveway.
I warmed the tractor up for a few minutes then got in position to start but to my surprise I only had front wheel drive, nothing happening at the rear tires.
If I push the diff lock pedal the right rear wheel has power and will spin. If I shift to 2wd nothing anywhere just like it's in neutral.
No unusual noises, never happened before. I thought maybe something was frozen since it's in the low teens outside, but after couple of hours of running and moving around in front wheel drive I still have nothing.
I know a stripped coupler can cause the front axle to loose power, but I'm not sure what would cause the rear axle to lose power.
Any ideas of something I can look at when it eventually warms up?
2006 Kubota B7610 hst.

 

[rScotty]

Now that's really an odd one. I can't imagine what it could be....or anything that could cause what you are seeing.
How about the range shift? Is it still working so that you have two ranges in front wheel drive?
Messicks has a parts manual online. Maybe it will give a clue.

 

[Eagle1]

Either left wheel spinning in the tire (low air) or that side final half shaft is not spinning. I would look to see if the shaft is turning when trying to move in 2wd. If the shaft is not moving time pop it out and look. If the shaft is not broken and splines look good you into the rear drive gears.
I guess the hub could have come detached from the shaft but normally that is welded into as part of the half shaft assy.
If the right turn with diff lock you know power is getting to final drive and the open diff just spins the side with the least resistance (left) until you engage the lock.

 

[vidio1]

Now that's really an odd one. I can't imagine what it could be....or anything that could cause what you are seeing.
How about the range shift? Is it still working so that you have two ranges in front wheel drive?
Messicks has a parts manual online. Maybe it will give a clue.

Yes both ranges work but doesn't change the front wheel drive.

 

[vidio1]

Yes both ranges work but doesn't change the front wheel drive.

 

[vidio1]

Either left wheel spinning in the tire (low air) or that side final half shaft is not spinning. I would look to see if the shaft is turning when trying to move in 2wd. If the shaft is not moving time pop it out and look. If the shaft is not broken and splines look good you into the rear drive gears.
I guess the hub could have come detached from the shaft but normally that is welded into as part of the half shaft assy.
If the right turn with diff lock you know power is getting to final drive and the open diff just spins the side with the least resistance (left) until you engage the lock.

Yeah I was thinking something similar, final drive, but it's too cold out right now to dig into very far.

 

[Eagle1]

Yeah I was thinking something similar, final drive, but it's too cold out right now to dig into very far.

I hear that, I several things put off until I feel my face and fingers.

 

[GrandpaSmurf825]

Are you sure that you have nothing even with the differential lock engaged in 2WD? It defies logic that you would have power to the right rear when the front end is engaged but not when disengaged. If it's not a rim slipping in the tire and hopefully that's what you will find it is. It's going to be a much more involved and expensive repair. It's easy in this cold for tire pressures to drop enough to loose the bead seal. It will be below 0 here tonight so you will probably be single digits above there.