I have sent an email to Ricambio and am waiting to see what happens.
Myself and a friend have had the car jacked up tonight to see what we can do. Both wheels have been off and we have tried several different ways to grease the pins, rotating the wheels while greasing, weight on the wheels while greasing etc. But to no avail, the grease just comes out the locking pin and goes nowhere near the bottom or top of the pin. The stub axle that is only 3 months old has a huge amount of play in it that you can actually see it moving, ironically more play than the older stub!
I will have to see what Ricambio say.