If you can tighten the bolts, do so as it will ex span the nutsert tighter in the hole and maybe reseat it. Either way, heat and lube the nutsert through a frame hole.
When it still spun, Ive used a prybar or apply force between the frame and bracket to pull the nutsert down with more force than what it wants to spin. It takes a few times and even a hammer to wedge it, but it has worked many times for me. Once out, tact weld them or replace with new nuts (and weld those)
1975 CJ-6 304 T15 Dana20 30/44 3.73
1983 CJ-8 258 T5 300 30/44 3.31 Looking for full or half hardtop buy or trade
1986 CJ-7 Laredo 4.6 stroker T5 300 30/44 3.31
1986 TJ-7 Trail Jeep project in the works
2003 Inca Gold TJ Rubicon