Hey guys,
My girlfriend has a 2000 Xterra 4x4 w/ manual locking front hubs. When we tried to take it off road yesterday, the right hub engaged without trouble. The left one, however, felt loose, and didn't click into the lock position. When the back wheels spun, you could hear the front right hub grinding, as though the mechanism was in the right place but not held in.

Is this a common problem? Being a Jeep guy, I haven't ever really dealt with locking hubs. I don't know if it needs to be replaced, rebuilt, or just greased. Any advice or links to sources would be greatly appreciated

Thanks guys!