As far as re-securing it: I'm not totally convinced this works but a mechanic I used to work with (he had a thing about not using the proper tools even when they were available. Didn't like to read instructions either but that's a rant for another day) would use a long bolt with a nut about 1/2 way up it. Screw the bolt into the rivnut with a couple of washers between nut and rivnut then hold the bolt still and tighten the nut (i.e. unscrew it). The theory being that you pull the rivnut tight with its own threads. If it doesn't work you won't have done any damage anyway and any half decent bike shop should have a rivnut setter an it's a two second job - looks like a pop rivet gun, you screw it into the rivnut then squeeze the handles.
Awesome!
As far as re-securing it: I'm not totally convinced this works but a mechanic I used to work with (he had a thing about not using the proper tools even when they were available. Didn't like to read instructions either but that's a rant for another day) would use a long bolt with a nut about 1/2 way up it. Screw the bolt into the rivnut with a couple of washers between nut and rivnut then hold the bolt still and tighten the nut (i.e. unscrew it). The theory being that you pull the rivnut tight with its own threads. If it doesn't work you won't have done any damage anyway and any half decent bike shop should have a rivnut setter an it's a two second job - looks like a pop rivet gun, you screw it into the rivnut then squeeze the handles.