Transfer Case Problem

I have a 1999 Nissan Pathfinder. It’s 4wd with a manual transmission. I was getting an intermittent problem with vibrations coming from the front passenger side wheel when driving on the highway. They recently got worse and I’d notice a slight burning smell coming from the wheel area. There would also occasionally be a metallic clicking/plonking noise coming from the wheel and a slight hissing sound. I took it into a mechanic (not my regular mechanic because he was gone for the week) and they said it has something to do with the transfer case. They said they took the front right tire off after putting it on the rack in neutral, and they couldn’t get the to spin freely. They said it could be something with the drive train or transfer case, but they weren’t sure without taking it apart. They said it could be something to do with the 4wd not disengaging, but again, they’re not sure. Anyone had any problems like this, and how much does it usually cost to fix?

If the truck has automatic locking hubs they are a likely cause of the problem.