driver side lock motor buzzing & not locking

i have a 98 grand cherokee; and just recently the driver side lock motor started buzzing when i try to open or lock the doors.
the other doors unlock & lock when i push the remote 2x, but the drivr side door does not.
this also happens when i try to lock or unlock them from the inside..
is there a relay or motor that need to be replaced or is it just a loose connection?
any help would be greatly appreciated..
thanx in advance..
The Fishman ?;o}

I've exactly the same problem with my 97 GC. A couple of days ago I sprayed the door lock mechanism with WD40 and used a screwdriver to pivot the locking bar a few times to free it up. So far the door's locked properly every time without buzzing.