Helicoils.

Returning briefly to the saga of the old trike, this is a handful of thread inserts with the tools required to fit them. I didn't include the dwang, perhaps I should have done, neither did I include the drill - it is too big.
A dwang? I thought you'd never ask, if you look it up on Wikipedia you come up with a nog, nogging or nogging piece - a bracing piece to used between studding or joists to give them rigidity; alternatively, it is a girl who pretends to be stupid in order to gain acceptance to a group, possibly including boys. I didn't know any of this, to me it's an engineering tool to hold the tap when tapping a thread; Google has no information about it at all.
To quote Anna Russell, "I'm not making this up you know."
Anna Russell? She's a story for another day.