https://www.weldingtipsandtricks.com/remove-a-broken-bolt.html
how to remove a broken bolt using a tig welder and oxyfuel torch…remove a broken stud from a cast iron exhaust manifold.
there are many ways to remove a broken bolt. Someone already gave it a try with an ez out and it was broken off in the stud.
lots of comments about using candle wax to help lubricate the threads. I will have to try that tip new time I need to remove a broken stud like this. However, the wd40 worked just fine this time. The heat from torch did the trick in expanding the surrounding metal in the manifold.