Get onto eBay and buy a M6 helicoil kit for about £20. They come with drill , tap, insrteion tool and about 25 inserts so you can replace all the threads at the same time. They'll never strip again.
I have M5 and M6 kits which cover most bike threads. I always helicoil cable clamp threads in gear mechs from new. It's always tempting to over tighten these. There's nothing worse than being out in the wilds, the cable slips so you tighten it up, giving the allen key another half turn just to be safe ........and it strips! Not with a helicoil it won't!
