Couple things that come to mind: If there is a misalignment of the transfer case relative to the linkage, the linkage can bind and cause the problem. Cause of misalignment could be bad motor/transmission/transfer case mounts, or even a slightly bent frame (Does the Tracker have a full frame or a front subframe?) A friend of mine once owned a new S-10 Blazer, hit a half-decent bump and then couldn't shift the transfer case. Cause? A bent frame. He's a pretty strong guy with a damn fine temper. I thought that he was going to tear apart the truck with his bare hands when he found out.

Problem 2 may be worn bushings in the transfer case linkage that may be binding it up.