Stuck cocktail shaker lid--help!

Forgive me if this is too far OT.
I just got a great old cocktail shaker, but the lid is stuck on tight. Normally, I'd resort to liquid wrench, hot water and maybe a sharp rap, but the body of this shaker is glass, and I don't want to risk breaking it. There appears to be a separate layer of some material (brass?) between the glass body and the friction-fit metal lid. I've turned the whole thing upside-down and soaked it in warm, soapy water, but that doesn't seem to have done the trick. Any suggestions would be greatly appreciated!

About 4 years ago Shelley bought an $80.00 Cocktail Shaker in New Orleans. We had the same trouble with the silver lid. When it got cold you could not remove the lid with a sledge hammer. Last year we saw an identical shaker with a rubber sealed lid for $10.00. The antique dealer had obviously taken a brand new retro looking shaker and added an old top. It makes sense, a metal top will outlast a glass shaker especially around people who are drinking. Shelley recently bought me a shaker in the shape of a zeppelin from Restoration Hardware. It would not seal. If you shook a cocktail in it, you would have cocktail all over you. We sent it back and got another one, it didn't work either. Maybe in days gone by it was a point of pride with craftsmen that whatever you made should work. Such an antiquated idea in this modern world.
Al

The coefficient of expansion of metal is greater than glass, so a series of very hot soaks will likely un stick it. I would actually do this as a project one night. First, soak it in hot, hot water with 409 or other "lubricant." Take your mixer and put it straight under cool water. That is, cool the glass. Wait! Can you get liquid inside? If so, put cool water in the glass, and run hot water over the metal top. You might even slosh the cool water up onto the metal and get a hot then cold action going. Eventually, it will loosen up.

It is likely just some dried cocktail mix in there. Do all this wrangling after it has soaked for a long time. Not just soaked, but move it around and twist a bit every so often to get what you can into the dried mix.