Well it's not easy but what I did was to heat to red hot a piece of round steel stock that fitted between the two steel inserts and pushed it into the rubber. Effectively burning the rubber, took a while as you might imagine. Once the rubber is destroyed the centre will come out. To remove the sleeve that remained in the hub I cut it with a hacksaw blade until I was able to close it up enough to remove it. Seem to recall it took me all morning and I stunk the place out! No doubt there's an easier way but removing this type of bush from a blind hole is never going to be easy. I did hear of someone using a milling machine to cut the blighters out but that involved removing the rim. If it's any consolation they are easy to refit!
