I took for granted it was the rudder pivot bolts dealing you a fit; I've impacted hundreds of pivot-bolts w/o a problem. Is it the four nozzle to stator bolts you cannot get loose? If so, like said above, spray 'em and wait a while.
I am not saying my way is the only way, however my tool of choice is my trusty impact. If the bolts are corroded, fwd/reverse bursts works well. I shy away from heat, it doesn't take much to damage the powder coat. In 15 years, I cannot recall snapping the nozzle to stator bolts. However, I've snapped countless stator-wear ring to pump housing bolts. If the corrosion has weakened the long bolts, they need replaced anywayz, thus I hammer away. If they break, I warm what's left of the protruding bolts to loosen the lock tight/pop off the corrosion. (they'll most often snap in middle, leaving enough to grab hold of)
Again, I restate, my way is my way, doesn't mean it's the only or best way. KT