Since you say "manual" I assume you have manual locking hubs with the knobs in the center of each hub and that you have a manual transfer case shifter (small shift next to main shift). If either is different let me know and I can possibly give more info.
Locking the manual hubs should not engage 4WD. All that does is connect the wheels to the front drive shaft. If you have the transfer case in 2wd there should be no problem. I drive like that most of the winter and over my three B2s I have probably put over 100K miles with hubs locked but in 2WD.
On the B2 with hubs locked and in 2wd, if everything is in good working order you can shift between 4WD (high) and 2WD at any speed without issue. In fact it is hard to tell it is shifting.
The 4WD does not have a front to rear differential so you can't run 4WD on dry pavement and even wet isn't recommended. Snow, mud and dirt is what it is for.
The binding you describe sounds very much like the transfer case is already in 4WD when you go and lock your hubs. That binding is what happens when you are in 4WD with hubs locked on dry pavement.
If you believe it is in 2WD it is either a transfer case problem, or it could be a problem with the transfer shifter key plate (the thing causes the pattern) being way out of adjustment so the little shift is too far back from the 2WD position and sitting in 4WD all the time. I had a problem with the key plate too far forward and it wouldn't stay in 4WD.
By the way, if you are in 4WD and hubs are unlocked, you will not get the binding.
A simple check. Park it, put it in gear, put it in 2WD. Have front wheel hubs unlocked.
Underneath you should be able to find the main drive shaft and the front drive shaft where it comes out of transfer case. With vehicle on the ground and it in 2WD you shouldn't be able to turn rear drive shaft, but the front drive shaft should turn freely. Do this by hand, don't try forcing with a wrench or you just could cause vehicle to roll.
With hubs unlocked and in 2WD, the front drive shaft and both axle shafts should turn freely.
With hubs unlocked and in 4WD, the front drive shaft will not turn (unless vehicle rolls) but it still should be possible to turn the axle shafts. In this case if you turn one axle shaft the other should turn the opposite direction.
If in 4WD and hubs locked, you shouldn't be able to turn the front drive shaft or either axle shaft in the front without the wheels turning/vehicle moving.
So see if it matches what it should be.
I suspect you are going to find that with hubs unlocked and in 2WD (assuming the binding you described was in 2WD) that the front drive shaft won't turn but the axle shafts will turn. This means either transfer case is stuck in 4WD for some reason (mechanical problem) or there is a transfer case shifter linkage problem or it is that key plate I mentioned.
For what it is worth, when you shift from 4WD to 2WD, if you do that while there is binding present, the transfer case can stick with 4WD engaged because whatever in the transfer case can't release with tension wound into it. If you suspect that is the case go in reverse a short bit can help unwind the binding. If you only engage 4WD in slip situations like mud, snow or dirt you usually won't wind in enough tension to keep it from shifting out.
