well, from experince… using a propane torch will get you no where as it doesnt like to get hot enough so really,l all you do is make a mess and then the rubber becomes like glue and if you do try to pry on it/remove it with a screw driver the melted rubber just sticks all over the screw driver making a mess of your tools… (I’ve read of people spraying something flamable @ it to increase the burn thou, hah)
now, if you have an oxy/acetylene touch which is 10x hotter, it melts instantly and falls out.
but like Bing said… chisel/hammer is really all you need and no mess to clean up or burning rubber to breath in