after upgrading to Firefox 17 the download-record-to-Zotero icon may presently fail to appear in the navigation bar

for more information see http://forums.zotero.org/discussion/26419/unapi-mods-translator-no-longer-working-in-zotero-3010-firefox-170/

you may wish to update your MODS translator immediately by following the link and instructions provided by Zotero developer Dan Stillman

we understand that the updated version of the translator will be rolled out soon