I certainly would not drive it any more until I knew what was wrong. There are a lot of expensive and hard to find parts in the front drive of these units. And further churning pieces of bearing, gear or even a roll pin in between gears cannot be good for them.
Second, lift the front end off the ground and rotate say your LF tire. Does the right front rotate too, even in the opposite direction? It should if things are still connected between the two. How does it feel? Smooth with some resistance? or like it is all by itself? With one front tire blocked and the transmission in 4wd you should not even be able to turn the front unblocked tire. Try with the other front tire blocked. With those tests then you probably can identify where the problem is located. From there you need a parts manual and repair, if it is the same front drive as yours. (I found out the front drive of the 186 is very different from my 1510).
Best of luck with it.
Mike