All 11cv owners should be aware of the fact that you never try to turn the engine over by pushing the car with the gearbox in gear.
Many otherwise strong gearboxes have been ruined by trying to jumpstart the car by pushing it in gear then engaging the clutch.
The gearbox design does not allow it to accept heavy “loading” of the ring and pinion which this causes. The fact that the aluminum gearbox housing is now 56 to 79 years old increases risk of damage.