grosporina

Thanks. I don't _think_ it's the centre hub, just because when I can see the play I can tell that the whole head's moving along with the pin but the shaft is not, so the pin's moving in the shaft, not in the hub. I had the same problem as you getting the old shaft out, I had to dremel it down to fit through the main shaft bearings and the swashplate bearing, but I haven't done a thing to the new shaft in that respect so it should be ok from that point of view.
Just in case it is the head/hub I'll take an old spare and try it out, though like I said all indications are the pin is moving relative to the shaft, not the head.