In Reply to: Broken Bolt Trans Cover - Extraction advice posted by Kimberly on March 31, 2021 at 11:54:30:
Unless you NEED to remove the transmission cover to get inside, I wouldn't worry about removing the broken bolt at this time.
Find another place to secure the wiring if necessary.
If you decide to remove the broken bolt now, my choice would be to get a set of left-hand spiral drill bills (approx $15). ...They are used in a reversible drill set in "reverse."
As the drill spins to drill a hole, the points of the bit generate some heat,and (because of the counter-clock rotation) try to un-screw the broken bolt. ...I would start with a 1/8" bit, and if that doesn't work, step-up to a 1/4" bit.
E-Z Outs often cause more problems than they solve.
Welding a nut to the broken bolt is a proven method, but if you haven't any experience welding, you may end up welding the nut to the trans cover, as well.