The stud unscrews from the case just like a
If there is enough thread left on the stud, you can take 2 nuts and put them on the end. Then tighten the nuts against
each other and use a wrench on the bottom nut to remove the stud.
Next option is use vise grips on the stud
that sticks out of the case.
You can take a vice grip and unscrew the broken stud. Then get a 6mm X 1.00 bolt to replace that stud.
You can also replace the stud with same to match.
If necessary you can also try cutting a slot in the end with a hacksaw and use a screwdriver to remove stud and replace
with bolt as above.
If it is broken off too far down for any of these options, then you will need to drill a hole in the stud. Then use
an EZ-out. You can get one at any automotive or hardware store. The studs are not hardened steel, so they can be drilled.
Use a center punch to mark the center. Then the drill won't wander off to the side.