1. I put all the heatset inserts and broken plastic around them back in place, and heated them with a soldering iron while squeezing the plastic around them with tweezers.
2. I put a few drops of acetone on each one to pre-soften the plastic.
3. After letting it dry, I carefully deposited baking soda around the weak plastic holding the inserts, getting it in any remaining cracks and building it up like chamfers around the sides.
4. I added drops of ultra-low-viscosity CA glue (Bob Smith Industries super-thin insta-cure, equivalent to Loctite 420 :weed:) one at a time until no loose powder was remaining, and let it all dry.