Revo 3.3 Tranny with all Metal Gears problem

Yes the idler gear is held on by that weird pin and wire clip ...don't know why they didn't use a nice set screw instead....can a machinist thread something hardened like this? I have a tap and die set, but your prob right it will laugh with its hardness at me if I try to thread it .....hummmm i'd weld it if the clutch was not aluminum and gear being steel....any machinists have any advice to thead this some way?