i see you are good mechanic. what happens with my bike is. Because the bottom bracket is was bad and i could install the other bottom bracket i had. i take the bike for opinion in LBS. the mechanic tell me the threads need chaced. I tell do that job because no have that tool. is do tye job okay. Ask me if i want install the crank i tell yes. But when i come home i see have install the crank arms in wrong angle.