While driving at third gear, a noise was suddenly heard in the gearbox and the vehicle remained in neutral. All the other gears are set without a problem. Is it possible that a synchronizer or a gear or even something worse broke down? If this ever happened to anyone before, please help me with the diagnosis. Thanks.
If it only happens with the 3rd gear, it must be that the gear rubbed against the axle; if the 4th gear is failing as well, it is the third and fourth gears shift fork.