[COLVERT]

Originally Posted by trikey

I prefer these to helicoils, far easier to work with.

https://www.timesert.com/html/catalog.pdf

A great idea but not necessary in this case as there's enough metal to take a new thread.

Helicoils are the answer where there is a shortage of metal and it would be impossible to form a new thread.

When fitting the new plug gentle force is all that's required to tighten it.

A small drop of thread lock or a small hole drilled through the head of the plug to fit a retaining wire. ( As per critical bolts in car or motor bike racing. ) There are many easy answers to put right stripped out threads. The clever bit is using the solution that solves your personal problem.--