ARB weld nut(s) damaged.

[Nuvo]

I've got a stinker of a problem with the M8 bolts holding one of the front ARB brackets.

The upper bolt is spinning in both directions and cannot be removed and the lower bolt can be removed and has some thread damage.
I'm not able to see the condition of the lower weld nut threads because the attached bracket prevents that, but I think it's probably safe to assume it will also be damaged.

If I'm very lucky and only the upper weld nut is damaged, is it possible to drill the head off the bolt and break the weld either with an air hammer?
Or drill out the entire bolt and then insert a strong metal rod into the nut and pry on it to break the welds off?
Still assuming that it is only the top nut that is damaged is it possible to tig weld a replacement weld in place? Would there be enough space to do that to a good standard?

Now considering the worst case that both welds nut need replacing, what would be the best method of tackling this? Drill off the upper bolt first to remove the bracket and ARB then cut out a panel which the nuts are attached to then grind of the damaged nuts, tig weld two replacements in place and then weld the panel back in place?

Does anyone have any direct experience of this or can suggest an improved way of fixing this please?
I won't be doing the work myself but I'd like to equip myself with knowledge and suggestions when I take it to an engineering place.

Thanks in advance for any help.

[Tractor Dave]

From memory, the welded nut is on the subframe upper edge. It will be difficult to weld new nuts in without removing the subframe. If you can get the old welded nut ground out in situ, I don't see why a new nut and a hefty lock washer wouldn't do until the next time you drop the subframe.

Another option would be to drill it and put a helicoil in there.

[Tractor Dave]

If you do take it anywhere to get welded, make sure they disconnect the ecu, battery and abs ecu

[Nuvo]

Thanks for the reminder Dave, I'll just be taking the subframe and ARB so that won't be a problem.

[Bowie69]

Much easier to just re-tap to M10 -the welded on nuts are firmly fixed, and won't snap off in a hurry (read bent subframe) and awkward to get to to replace.

So either re-tap or fill with weld, drill and re-tap would be my preferred solution.

[Mikes2]

I had this. Took the subframe off the car. Used a spanner to hold the spinning nut and extracted the bolt. Got a machine shop to remove the bracket and weld the nut back in place. The bracket then got welded back on the subframe