Good job Grigg!!

One other ideal that I have used before, to get a hardened set screw/bolt out.
Take an old broke off tap and sharpen it like a drill bit.
The web is already there.
Maybe even sharpen it to be left handed, so when it starts to break thru, it will unscrew the bolt.

Again
Great job and John owes you for your skills.

Don

1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!