In your excellent tutorial you write “8. Now here’s the trick, pump the pump really hard until completely firm”
Very likely you are speaking of the “low pressure feeding pump” that is sitted on the left and bottom side of the engine. See picture attached : the lever one has to manoeuver is designated “poussoir manuel pour réammorcer, peu efficace” which is French for “manual lever for bleeding, not very efficient”.
Apart from not being efficient it should be pointed that the lever may be totaly innefficient when the camshaft that acts upon this pump is – by ure hazard – in an innapropriate position whereby the mecanism inside is resting in “pressed” position while it should be (and most of the time it is) in “rest” position. Should this happen just rotate the engine a bit using the starter engine.
On Naîla previous owner fitted a bleeding pump that is owerwhelmingly efficient (See attached picture with the big black button to activate bleeding). Does anyone know the name and the manufacturer of this pure marvel.