Okay. Replacement Nobby Nic 3" arrived yesterday. Still super tight to fit, however I think I have it sussed. Three of the heavy duty Park Tools levers are required. First one in and hooked on a spoke, second has to be almost next to it, say one spoke away. Again hooked and third one on. Middle one out and almost next to the third and it s off. You just need super tough levers that can take the force required, and just inch away slowly. Refitting, same technique, little and often. Plus a little dilute washing liquid on the last section of rim. So now I'm packing 4 of the PT levers at all times!