Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Some heads they all let go, seems to depend on the previous life of the engine, Helicoils are ok as a fix but can wind back out again sometimes - I have been told timesert is a better alternative that adds serations to the insert so it is less likely to wind back out with the bolt. I have yet to try a timesert as I have a fair number of helicoils to use up.