Buzz, if I'm not mistaken, you are talking about an L.C. Smith. If the lever goes too far to the left, it is possible the extension rib slope is worn and can be TIG welded and then filed to correct this.
Also possible the rotary bolt is worn, but my guess would be the extension rib slope where the rotary bolt goes through it and tightens up on the slope of the extension rib.

If it is not an L.C. Smith, sorry.

David