Depending on how much thread you pulled out, it would be better to use a slightly longer bolt if possible. The thread inserts are only about 5mm long, so if you were to helicoil the mount you would only be able to put 5mm of new thread in, unless you can get longer thread inserts (which I'm not sure if you can). I have helicoiled 1 bolt hole on my old frame and all 4 on my friends frame, all which I only tapped to about 5mm deep as they all the holes had some thread left at the bottom. Helicoiling is easy, just follow the instructions and you'll be fine.