AFP Locked Files

Has anyone found a way to unlock files that appear to be in use by an AFP client? This seems to happen most often with Quark files on our Panther Xserve. lsof does not appear to list files opened by clients accessing them via AFP over the network. Of course, restarting AFP is not an option. We typically have to restore the file in this scenario. I have found other posts related to this issue but no replies. Strange that this solution is so hard to come by... If unlocking the file is not possible, does anyone know how to identify which user last opened the file? Keywords: locked open files afp unlock lsof