Repaired a fuel tank a few months back that had a loose captive nut.
The insert was fine until I tried to drill out the broken bolt and then the insert spun.
I ended up using a Dremmel to bore some holes about 1.5mm Dia down halfway in the brass and plastic. I think Toolies call this a scotch key.
I think it was a engraving tool I used to do it. While you could do it with a drill bit you will find the the drill will naturally drift into the softer plastic and the hole needs to be half and half.
Then I just stuffed the gaps with Araldite and used some 1.5mm welding wire in the holes to lock it in place. The Araldite doesn't actually come in contact with the fuel, just the fuel residue that comes through the plastic.
Seems to have worked okay but I only put fuel in it once to then discover that the tank had been melted through onto the exhaust so it now just sits in storage.
