Associating an Application (Gnome)

During an APT Gnumeric package update, something went wrong. The problem has been corrected but in the process, gnome lost track of the file association. I want the file associated with Gnumeric. I can get all the way to the Edit File Type dialog box but I can't complete the association unless I enter a MIME type. This confuses me some since there is a MIME type there already (zz-winassoc-xls). Can anyone offer any suggestions on how I can get Gnumeric files associated with MS Excel files? Thanks for any help. Don Henson