Tightening the side edge. Lever is free.
After it originally slipped, I took the shifters off then added them back. Possibly, from what I read here, I need to remove the shifters, insert a bread tie into the shifter (without a cable that stayed intact), dissassemble that one - get a correct exploded view of how all parts go together - then put both back the correct way in case I accidentally changed part order when removing the shifter assembly to check it out why the bracket was slipping.