[Arran]

George, Mike;
What I have done in the past with potted condenser cans, not Philco ones by the way, was to melt the tar out of the bottom, drill a hole in the center of one of the layers, drive a large screw into it, then put the can in an OLD toaster oven for maybe 20 minutes at 200 degrees Fahrenheit (or as close as you can get). After the can is hot you can then pull at the screw with a pair of pliers till the section it is driven into comes out, and the rest will follow. An alternative would be to place the can on top of a steel plate, on top of a hot plate.
Regards
Arran