It doesn't have a lock, just you have to push it outward to move it back to 2wd, and then it snaps over a detent. Is that what you are referring to? The only times I've heard of the 2wd jumping in or out was with the tank shifter.
I will try to get some rides and ride reports posted, but with getting married this summer it is cutting into my riding time, but with the Ural my riding season is extended
That sounds like it.