[elmariachi]

I have used Timeserts and although they show the tap being turned in by a drill in the video, in this case I would do it by hand using a tap handle or Crescent wrench, so that you can go slow. And doing it by hand will help keep it plumb, though I think that wil take care of itself once you get the bolt out. Unless this bolt is in a completely blind spot, if you can drill it out then you should be able to get the insert in.