Answer
OK, I discovered the trick:the pulley is on a reverses thread - rotate clockwise to undo the pulley, then fan and bearing slide off the armature.
front bearing
Lovely job - and well tackled.
I need to replace - or lubricate my front bearing too, and replace the fan blades which are a bit tattered. The Motor is out, but before I use any force, I would like to check , how is the fan and belt pulley removed from the armature prior to...