Try chasing threads with bottoming tap and use original puch stud which threads cleaned and chased
Thread insert is kinda big and meat on za50 by transfer not too much,
What I would do is drill out the 6 mm hole to a 7 mm stud if chasing don’t work and then if that don’t work
What I did I did before (by hand) Is drill out to 8 mm hole and tap, drill a hole into a 8 mm bolt about 1/2 inch tap it and cut it off, smooth edges and use it as an insert, you only need about the size of a nut to have good threads, I've done this all with the hand drill on a bike but it helps to have someone tell you if you’re holding the drill at the right angle,