Extraction Of Damaged Thread Insert
Alternative 1
File a notch in the thread insert, about a quarter turn in from the end. Do not file through the insert.
NOTE:
Do not damage the thread in the material.
Use a triangular scraper or similar to extract the insert by rotating it.
Alternative 2
Carefully expose the end of the thread insert. Use flat-nose pliers to pull the thread insert out.
Clean out the threads in the hole using the thread tap and blow clean.
Install a new thread insert.