I got the secondary off my son's 90 Indy by just prying with 2 large screwdrivers,and it popped right off. Giving the back side a little rap with a rubber hammer or a block of wood will help it along. After it is off, use emery cloth to polish the rust off the jack shaft and put anti-sieze on it, and it will slide off by hand next time.
Squirt some WD-40 on both sides of the shaft if it does not free up. That pulley is supposed to have some side play along the shaft, I've never came across a siezed one. It's usually fairly greasy in that area because of the bearing. Be sure the grease that bearing while you have it off.
It is rusted in place. It is supposed to float on the shaft about 1/16 to 1/8 inch end play. It should be removed and the shaft cleaned and greased periodicly to avoid seziure to the shaft. It is recomended to do this at the end of the season before summer storage.
If you have the clutch with adjustable clutch sheaves remove the three bolts that adjust the clutch. You can put 1/4"x20 bolts in these holes and use a puller on it. Make sure you use something to protect the end of the jackshaft and threads.