drive your car for about 10 minutes (to heat the metal and so its in it's most expanded form). then while wearing thick gardening gloves (or oven mitts if you don't have the gloves), and players - it should easily come out... muffler shops will just use thier tourches to heat the area, and then tools to remove the parts
(about $10 at your local shop... Maidas or whatever)
if you are still having problems, use a flathead screw driver and rubber mallet.
And always remember, Wd40 is flammable... so if you are going to use that while your car is hot, at least make sure your car is turned OFF... and after using that stuff, wipe the areas down throughly, to remove all remaining traces of the formula