[Mondial]

That part is usually referred to as the switch detent assembly.

Is it possible that the whole shaft has shifted backwards so the rotating bar no longer contacts the bumps? There should be a groove with a lock ring in front of the switch bushing which prevents the shaft from moving axially. If the lock ring is missing then the shaft can move backward and the bar will no longer be in contact with the bumps.

Can you slide the shaft forward so the bar contacts the bumps?