Hello:
You can also get your hands on an old microwave oven.
A 20 second blast will usually warm up the old creosote that is holding the insulator to the pin. Once the hardened creosote was turned gooey, the insulator can be removed from the wooden pin.
Don't do this inside the house. Some pins make a heck of a stink, even with just 20 seconds. Sometimes an extra 10 - 20 seconds is needed, but not very often.
Now don't laugh at this idea
I've done 100s of insulators this way. I let an old 143 ( old glass ) go for over a minute and the pin did not cause any cracks. I think there was a crack or two from other imperfections in the glass, but no explosions of any sort. There may have been one insulator crack on me doing it this way, but it is a very rare occurance.
I have done rare insulators this way, all though I did it with 5 second blasts to minimize the stress potential etc
My only warning is to look for metal, either in the pin or bits in the insulator. Oh, and don't use the good microwave from the kitchen. Creosote is not nice stuff to have around unless you are preserving wood.
Good luck ............ Robin