Rusted area

Careful inspection on the share planes of the broken stopper bolt for accelerator wire end of the throttle arm in Bocar 34PICT3 carburetor led me to the conclusion that the criminal of the accident was not always myself alone, because there found considerable rusted area on the tone surfaces.

In short the destruction of the stopper bolt had been begun and just I applied additional torque power for tightening then natural physics phenomena happened that's all.
So, I count it as an early failure of the product, 40 years later from the machine production.