Dry Ice on the shaft to shrink it helps too,
along with gentle heat like a light bulb on the pulley.

Many grocery store chains sell Dry Ice and it is cheap, typically $7 per pound at Publix stores in Florida, for example.

If you can't find Dry Ice
these 'Freeze It' sprays are helpful too

http://www.crcindustries.com/ei/content/pst.aspx?PID=Panel2_3

http://www.amazon.com/CRC-05222-Freeze-Off-Super-Penetrant/dp/B000KKCQUW

http://www.loctitefreezeandrelease.com/instructions.htm