take the bolt out and spray heaps of WD40 in there. Keep doing it every 30 mins or so or until you get jack of it. The next day, take a "hard" soft faced hammer and Lightly tap it ON. Hit it about as hard as you would to start a nail into a bit of wood. It should be just enough to break the rust and stuff that has formed between the crank and the pulley.
The other (better) option is to get a proper puller. There are 2 x M6 threads in the pulley spokes. Use them with a puller to get it out. When you put it back on, put antiseize on the shaft and loctite on the thread.
