92 LaSabre Crankshaft position sensor

I am trying to replace the positioning sensor. I have to pull the harmonic balancer. I got the center bolt out of the balancer but it will not come off. The manual (Haynes) says that the balancer should pull off by hand. Any advice? Is there a trick or something?

Actually the balancer is a press fit on the 92 and you will need a puller designed for that application.This link may help:
http://www.automotiveforums.com/vbulletin/showthread.php?t=505203&highlight=harmonic+balancer