Google Calendar sync not working in Mountain Lion

Last week my OS X Calendar stopped syncing to Google Calendar. Past events are still there, but new events aren't pushed to Google anymore. I already tried deleting Calendar's/iCals Cache and Settings, removing the Google Calendar entirely and adding it back again. No success so far. Does anybody know about a way to debug CalDAV syncing on OS X? Is there a issue with Google's servers? Any help is appreciated.