I know I’m only a year or so late but…
It stay away from torches. Even if it doesn’t crack the glass now, it will probably put stresses in it. Same goes for hard rapping ( even with a wooden spoon).
Soak it in coca-cola overnight. This is an old glass blower trick that works more times than not…
If you do end up beating the hell out of it to get it loose, take it to your local glass blower and ask them to throw it in their kiln for an annealing cycle. Done properly, all stresses will be relieved and it will be back to original strength.
Credentials: 23 years as a glassblower