no, the nut-sert is not soldered. if you have a nut-sert tool, you can sometimes squeeze the nut-sert again and it'll tighten back up and not spin.
i have the tool to do it and would be happy to fix it for you. worst case senerio would be a new nut-sert is needed. i have them as well. i'll fix it for free if you pay the shipping both ways.