How to remove a Flymo Venturer 32 motor pulley?

I'm trying to strip this motor so I can remove and hopefully replace the lower ball race which has started to seize up. I've removed the armature from the motor and now need to remove the belt pulley from the motor shaft. It appears to be a tight interference fit but I can't find a way to get it off. I don't have a "proper" puller which may help, but I tried using a ball joint splitter which just fits between the pulley and fan. No amount of force will get it to budge! In fact the bottom flange on the pulley started to bend before I gave up!

I don't know if there's something else I could try. As the shaft is part of the motor armature it's not really possible to heat it. Anyone ever succeeded with this?