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Everyone's pretty much already said what I was going talk about, but here's a picture of the last stubborn one I removed.
I did soak it with CLR and various penetrating oils to no avail. A little careful heating with the little torch did the trick, but the heat did shatter the glass. The turning tool I used was made from a washer as seen at the bottom of the picture.
After heating it, how much force did it take to get er' loose? I don't want to be dealing with hot parts and still be putting 500footlbs of torque on it, then it snaps off and flies into my eye ball and burns it.