HOW 2 AF how to remove a broken bolt deep in a hole. It's easy to remove a broken bolt in a recessed hole using Harbor Freight Screw Extractor kit.
Drilling out the center of the broken bolt that is stuck in the hole. The drill bit must be in the center of the broken stud or bolt. I started with the smallest drill bit and worked up to larger size to match the No 3 extractor. Extracting a steel bolt out of aluminum cylinder head. Broken valve cover bolt easy out with this extractor kit. Keep checking the depth of the hole to the extractor don't want to drill too deep. Once the extractor starts to bite onto the broken bolt or stud soak it with lubricant and use steady force turning it out.