I removed the strut braces from my car, to find that on two of the holes at the bulkhead end the thread is missing, and the bolt had had a couple of bolts put underneath.

I saw a video from Raymie's Garage where he had the same problem, but he had the insert. I don't have the inserts.

Is there a way to obtain and attach an insert?

Click image to enlarge

I'm not familiar with the particular part as such but it looks to me very much like it could easily be fixed with a rivnut/ nutsert (others available I'd guess). How easy it might be could depend on the size of the hole and the required thread, but I'd imagine there would be different wall thicknesses and grip ranges available. A rivnut is installed pretty much like a pop rivet, but without the pop.

Chris