Chainsaw Repair

Over the weekend had a few minutes to look at this saw and the helicoil and try work out what had gone wrong. My thoughts are that neither the helicoil or the stud were loctited home so when I was tightening the bar nut it was spinning the stud in the helicoil driving it in until the stud bottomed out on the hole then proceeded to push the helicoil out. The broken 1/2 of the helicoil is stuck on the now free stud and the thread that was cut for the helicoil is stripped and burred.
So my thoughts are to retap and put in a larger bolt then remove and tap the excess down to 5/16 x 20 tpi   or would it be stronger to tap the large thread insert the bolt cut off the excess and thread the centre for the 5\16 stud. Thoughts from guys who are more experienced in metal work than I am would be appreciated
Which would be the stronger of the two cheers